Attilas's Dyno Test

[saddle up]

Wow Dan,

I am way out of my league when it comes to you and the other Guru's.
It seem's to me that some experimentation between the 78/79 which had the part mechanical advance along with the vacuum advance, and the 80 and later, strictly vacuum advance. Correct me if I am wrong, but didn't the 78/79 have flyweights and springs??? And the 80 and later is just vacuum? Plus the different initial and advanced timing differences between the two
Nonetheless an interesting and thought provoking read. Good luck

[Dan Hodges]

Re: Wow Dan,

Originally posted by saddle up
I am way out of my league when it comes to you and the other Guru's.
It seem's to me that some experimentation between the 78/79 which had the part mechanical advance along with the vacuum advance, and the 80 and later, strictly vacuum advance. Correct me if I am wrong, but didn't the 78/79 have flyweights and springs??? And the 80 and later is just vacuum? Plus the different initial and advanced timing differences between the two
Nonetheless an interesting and thought provoking read. Good luck

Maybe I was not making myself clear when I was talking about engine vacum and it's effect on the carb diagraphm's and their rate of lift. When you increase the duration of the cams or alter the centerlines, it effects the engine overlap and the more overlap you have the less vacum you will have at idle but the more you will have from about 2,000 rpm on which is why Holley makes power valves for their carburetors from increments of 1.5 inches of Hg to 20. Cam overlap is computed from the intake opening and the exhaust closing figures. Basically, the higher the volumetric efficiency that the motor achives the more vacum or draw it will have as an engine is nothing more than an air pump. It is also true to a certain degree that more or less engine vacum from whatever modifications you make will also effect the vacum diaphragm for the ignition advancer however it will be minimal at idle and advance at WOT will not be effected. The 81 didn't use the spring and weights in the advancer like the earlier models but still made use of a vacum diaphragm to advance the ignition lead under load and the TCI box had a fully electronic ignition curve which gave 35 degrees at 4,000 rpm and this coupled with the 5 degrees of initial at idle gave you a total of 40 degrees. The advance curves for all models can be found in the shop manual. The timing mechanism of the 81 can be modified in such a way as to allow you to advance or retard your timing based on what ignition advance/lead the motor wants and this will depend on your pumping compression. Pumping compression is primarily affected by the intake valve closing, static compression and altitude. At 5,000 feet, you need more compression and you can use more ignition lead than you would use at sea level. Generally speaking, more ignition timing will give you more low end and sometimes midrange power but will almost always come at the expense of top end. Hopefully this has answered your question about vacum. Oh yes, I'm not a Guru, just plain ole Dan.

[Bigleo]

Hi Dan,
thanks for publishing your dyno information, very informative. I think running some smooth bore carbs, without the restrictive butterfly valve of the stock carbs, you would easily break the 100 HP mark. I think the airflow restriction of the butterfly valve, even when it is at the wide open postition, is often overlooked. As far as streetability goes, I have found that my smoothbores are much easier to control that my stock CVs ever were.
In my opinion the rich mixture you are finding at low rpm is caused by the hotter cams. What is happening is that the intake valve now stays open past BDC for an extended period of time. At low rpm, as the piston starts the compression stroke, some of the air/fuel mixture is pushed back out through the carb. This previously carburated mixture then waits in the velocity stack and carb venturi area until the next intake stroke, when it is carburated for a second time as it is sucked into the engine. As some of the next intake charge is carburated twice, you end up with the rich situation. As the engine speed picks up and you get into the camshaft's peak torque range, this no longer occurs. This is due to the intake air flow getting enough speed and momentum to conteract the piston's effort to push air out of the intake. I don't think there is much you could do to correct this. If you set it up to run correctly at lower rpm you would end up running really lean in the mid range.
I am looking forward to hearing about your 1300cc motor and its dyno results.
Leo

[mro]

Oh yes, I'm not a Guru, just plain ole Dan.

LOL....
Imagine you've forgotten more about high performance engines than I've ever learned.


mro

[Dan Hodges]

Originally posted by Bigleo
Hi Dan,
thanks for publishing your dyno information, very informative. I think running some smooth bore carbs, without the restrictive butterfly valve of the stock carbs, you would easily break the 100 HP mark. I think the airflow restriction of the butterfly valve, even when it is at the wide open postition, is often overlooked. As far as streetability goes, I have found that my smoothbores are much easier to control that my stock CVs ever were.
In my opinion the rich mixture you are finding at low rpm is caused by the hotter cams. What is happening is that the intake valve now stays open past BDC for an extended period of time. At low rpm, as the piston starts the compression stroke, some of the air/fuel mixture is pushed back out through the carb. This previously carburated mixture then waits in the velocity stack and carb venturi area until the next intake stroke, when it is carburated for a second time as it is sucked into the engine. As some of the next intake charge is carburated twice, you end up with the rich situation. As the engine speed picks up and you get into the camshaft's peak torque range, this no longer occurs. This is due to the intake air flow getting enough speed and momentum to conteract the piston's effort to push air out of the intake. I don't think there is much you could do to correct this. If you set it up to run correctly at lower rpm you would end up running really lean in the mid range.
I am looking forward to hearing about your 1300cc motor and its dyno results.
Leo

My cams are actually not that radical and when you whack the throttle at 2,000 rpm it pulls like my tow truck but the slides are opening too quickly with the stock springs when used with the stock needles and that's when the rich spot at 2500 rpm occurs. With the V-Max slide springs it doesn't have that stumble but I agree that it would be better if you used a weaker spring where the slides would raise quicker but this configeration will require a needle that is longer and has a more gradual taper than the stock needles have. The DynoJet needles installed in the second position from the top (recommended in the jet kit) cured the 2500 rpm stumbles but was so lean at 5000 rpm it quit pulling and I aborted that dyno test. In the next couple of days I'm going to give the DynoJet needles and stock springs another try with the clip position moved down 3 clicks and this should make a noticeable difference. The most important event in the opening and closing phase of the camshaft is the point where the intake valve closes as this has the greatest effect on pumping compression because the piston is on it's compression stroke and this is why advancing the cam will generally give you more low end torque at the expense of top end and of course it increases the overlap. If you advance the intake 4 degrees, it closes 4 degrees earlier (abc) and opens 4 degrees earlier (btc) and adds 4 degrees of overlap. Your explanation about what is happening regarding the camshaft is essentially correct however some of these tuning problems can be resolved with CV carbs untill the cam gets into the 265 degree range (@.040 checking lift) and then you will need smooth bores and lower gears. Years ago I built a big inch (1314) 1100 FJ with a set of cams similiar in duration to these and I used a set of 33 mm Mikuni smooth bores and they worked good but I wanted to keep this one stock looking with the stock carbs. As I recall, you could not whack the throttle of the killer FJ to WOT untill you reached about 4,000 rpm in high gear. 1st., 2nd. and 3rd. were totally evil but below 4,000 rpm in high you simply rolled it on because if you didn't it would gag on the big smooth bores. Actually the little tuning glitch I'm experiencing is nothing compared to some other problems with motors I have had over the years and it will be fixed within the month. Thank's for your interest in my projects.

[Dan Hodges]

DYNO-Jet Daze

I've continued with my carb tweaking and now that it's Rocktober I've finally hit on the perfect combination. The instructions in the dyno-Jet kit recommended drilling the slide lift holes from the stock diameter of .093 out to .099 with the #39 drill bit provided. Because of the increased overlap of the Mega-Cycle cams I'm using, this was causing the slides to open too quickly which was causing my fat spots at 2500 rpm and again at 4500 rpm through about 5500 rpm. I tried several different spring combo's including a new set of V-Max springs but all of them had varying degrees of problems. With the V-Max springs I used the stock needles with the plastic donuts shaved .025 and this cured the 2500 rpm stumbles but it was sort of flat at 7500 rpm and up. In desperation, I bought a new set of slides from Yamaha so I would have the stock size lift holes (.093) and re-installed the Dyno Jet combo with the needles dropped one click from the recommended 2nd. groove from the top along with the DJ # 190 pilot air jets and DJ 128 main jets. Per DJ's recommendation, the idle air screws are 4 turns out from lightly seated and the pilot jets are stock 42.5. Because of all the problems I had experienced with all of the other combo's I simply didn't think this would work but it did. Yesterday, (Sunday) I took it for a 150 mile flight on the Illinois Interstate and it runs like a rocket. I rolled it on at WOT starting at 2000 rpm and let it eat untill it approached 8000 rpm and it didn't have one glitch. From about 5500 rpm untill I backed off at 8000 rpm it pulls like my V-Max but it's not as stout as the Max is down low. DJ wasn't very helpfull in this ordeal and simply advised that my combination was outside the parameters of the kit. Trying to compare the DJ jets which go by drill sizes and the Mikuni jets which are measured by flow sizes is an exercise of insanity and even though you might get close there is no direct correlation between them. Of course this is all seat of the pant's stuff but it's noticeably stouter than it was when I had it on the dyno back in July and most importantly it doesn't exibit any of the glitches/fat spots that it had then. Most guy's tend to shy away from using aftermarket cams on both intake and exhaust and use a big intake cam with the stock 80-82 exhaust cam which has a weird centerline (113 degrees) which decreases the overlap however this limits power and torque because of the limited exhaust flow compared to the intake but because of the reduced overlap it's easier to get the CV carburetors to work. My camshaft's have 40 degrees of overlap checked at .040 lift compared to less than half that using the 80-82 exhaust cam with the 257 MegaCycle intake cam. In retrospect now that I have my carburetors scienced out, I think the hot set up for a street 1179-1196 would be the stage II Web intake cam advanced 4 degrees and the 257 MegaCycle exhaust cam in at 108 degrees. My 257 MegaCycle cams are now both in @ 108 degrees per the cam card versus the 104 degrees on the intake cam when I had it on the dyno. At that setting, it made a boat load of torque but was down 2 or three horsepower from what it should have been but we live and learn. These old two valve heads like a lot of valve lift but anything over .400 requires clearencing the head for the cam lobes and anything over about .425 requires a shim under bucket follower and possibly shortened guides. Hopefully my shared experience will benefit some of you should you decide on stepping up to a set of big camshaft's. With the economy in free fall and the elections three weeks away, an XS Eleven might wind up being the only thing I can afford to drive.

[81xsproject]

I started reading this at work a few days ago, but had to quit. I just wanted to thank you again, Dan, for another great write-up. I can't wait to read more on the 1311, too.

[yamahansolo]

why not get a progressive spring one that has less coils at the bottom and more at the top.. like the progressive fork springs...

[Dan Hodges]

An Excercise Of Insanity

I started reading this at work a few days ago, but had to quit. I just wanted to thank you again, Dan, for another great write-up. I can't wait to read more on the 1311, too.

I'm pleased that you got something from my mechanical meanderings because I've spent more time tweaking that old Eleven than I care to imagine. As far as the 1311 goes, it should with all other factors equal, make about 10%-12% more power than a 1179 however a larger bore unshrouds the valves and increases air flow but at the same time it takes more time for the flame front to travel across the larger bore unless the spark plug placement is changed which in this case it will not be changed and so more ignition timing will probably be needed. The Eleven has that monster 14 mm spark plug when it should have a 12 mm because the 14 mm plug limits the size of the intake valve and the placement of the plug itself however I didn't design the damn thing somebody else did and so it is what it is. This winter I'm going to do some port flow analysis on a flow bench using one of my spare heads in an attempt to determine at what valve lift the air flow through the port stalls so I can determine how much valve lift I need when I get my next set of cams ground. The head I'm using on the 1179 was done by Patrick Racing but they didn't flow it with more than .400 lift because I had told them I would be using a cam with only .375 lift. The head I'm using on the 1179 might not be big enough for a 1300 but that's one of the things I need to find out because too much head is sometimes worse than one that is slightly small and I don't mean just volumn but total air flow. On the Eleven you cannot get too crazy with cams, cylinder head air flow and carburetors and keep it streetable because it's got shaft drive and you can't change the gear ratios like I did on my old FJ-1100. If it were simply a matter of top end horsepower you could cam it and port it to the max however it wouldn't be pleasant to ride. This is a picture of the intake port of the head that's on the 1179 and it's fairly well developed for an engine in the 1200 cc range.





All of this stuff is subject to change as it's a work in progress. Have a good one. Dan

[Paintman]

Great Info

Also good to read what another OC gear head comes up with i had to tear mine down this week and im going to tweak her a bit i was looking into teh web cams as i have used them alot in the past. i just want more power since its a full dresser with me and passanger all the time. i have another 11 all torn down and 3 sopare engines to play with that one i will follow similar path as you since i will be only one riding it. its fun to see what we can pull out of 30 yo technology now if this had been a 4 valve head then it would realy get interesting. i use to build molds for a foundry and we would cast heads custome cranks. to make a new 4 valve head would be fun but cost would be insane..

Once again Dan thanks for all the good info.

John

[Dan Hodges]

4 Valve Head vs 2 Valve Head

A 4 valve head configeration will make about 8%-10% more power than one of a 2 valve configeration. There are good and poor examples of both however I'm quoting what is considered to be the difference between good examples of both designs. From a strict engineering standpoint each design has it's advantages along with it's disadvantages but at the end of the day, a naturally aspirated engine with a well developed 4 valve head is equal to a similiar engine with a 2 valve head having 100 cc's more displacement. It might be worth mentioning that in NHRA Pro/Stock motorcycle racing the Suzuki's are the dominant Japanese make and the 4 valve motors are allowed 1429 cc's and the 2 valve combinations are allowed 1508 cc's both having a minimum weight including rider of 600 pounds and if you follow this motorcycle drag race thing you will note that the 2 valve motors are dominant with few teams using the 4 valve stuff. Of course the Harley Davidson's are competitive in this class too however they are allowed up to 200 ci (3280 cc's) and the same 600 pound minimum weight which is twice as big as the Suzuki's or other Japanese stuff but NHRA choose to do that in order to make the Harley's competitive due to their popularity. Attached is a picture of what is considered to be the ultimate 2 valve race head and you can get one made for your favorite Eleven............if you want to spend the money.

[Elevenator]

Interesting read and informative.

But...

Did you ever get a good dyno run on that beast (Attila)? The graphs you posted looked a little bogus. I read your clutch was slipping at the time. No doubt that has long since been fixed. I would suspect a trick 1179 with the porting work and cams you had in it would make a little over 100 hp at the rear wheel.

Thanks again for sharing.

[Dan Hodges]

Bogus Test.....But?

Interesting read and informative.

But...

Did you ever get a good dyno run on that beast (Attila)? The graphs you posted looked a little bogus. I read your clutch was slipping at the time. No doubt that has long since been fixed. I would suspect a trick 1179 with the porting work and cams you had in it would make a little over 100 hp at the rear wheel.

Thanks again for sharing.

Both were not good as in the first test I was suffering from the fat condition in two places and the original stock clutch would not hold it after 6500 rpm but it still slipped out 94 horses and 70ft. lbs. of torque.The printout of this test that I posted might have looked a little bogus but if you look at it closely, it's pretty self evident as it shows the funky fuel curve and where the clutch began to slip at 6,000 rpm and where Widman nailed it again at about 6,800 and shut off at 7,500. In the second test with a new clutch and the same jet setting it made 95.58 horsepower and 73.95 ft. lbs. of torque. The power curve was still climbing but I didn't want to take it over 8500. The fuel curve on the top end was okay (13) but fat on the low end (2500-3500) and again 4500 to 5500 rpm. The print out of that test which I posted with the corrections read double of what it showed on the computer screen which showed 74 ft. lbs. of torque @ 6,000 rpm. In those test I had the cams installed at 104 degrees CL for more torque which was a mistake because it made gobs of torque but was down two or three horsepower from what it should have been. In September I installed a Dyno Jet kit and put the cams in at 108.5 degrees CL per the cam card and did another test at Widman. The DJ kit cleaned up my bottom end starting at 2000 rpm however with the DJ recommended #128 mains it was in the 14 range on the A/F on the top end which is a little lean. With this combo it made a tick over 98 horsepower and 72 ft. lbs. of torque. I have since increased the mains to a DJ # 132 but I haven't did another test. I do these test to get a general idea of what I got power wise but primarily I do it to get my fuel and power curve. With a printout it's 50 bucks a pop but with the bike on the stand Widman will give you a few pulls for the same 50 bucks and you can write the results down yourself. With some more fiddling I'm sure I could fetch another 3-5 horsepower but those WOT runs on the dyno are hard on parts and I'm satisfied with what I have and I believe I now have it dead nut on. The cams I have are not that radical duration wise ( 10 degrees more than the 78-79 cams with .050 more lift) and are designed for strong mid range power however a set of cams with a little more duration would perk it up on the top end but would cost some below 5,000 rpm which I don't want. A box stock Eleven in good shape with the stock pipes will only fetch about 72-74 horsepower and 55 ft. lbs. of torque and presently I'm making over 30% more than that and for now that's what the (little 1179) has which is a good increase. If you increased the power of a stock V-Max by 30%, it would have over 150 horsepower at the tire, a power to weight ratio which would be better than the 09 Max (700 lbs.& 174 hp at the tire). I believe the biggest horsepower numbers besides mine ever posted on Channel Eleven (96.2 hp & 68 ft. lbs. tq.) were those of Maximan's (Cody) and his combo was an 1196 with 36mm FJ carburetors and a port matched head cut 024, Web stage II intake cam, pipe/pipes and lot's of dyno time. If you look at that first test of mine again you will see that even with a slipping clutch and a screwy air fuel ratio I had him covered. I'm working on a much bigger new motor now with some trick Ross pistons, larger carburetors and bigger cams (more duration) which will fetch some stock V-Max (original model) size hp numbers. My 96 Max with some fiddling is now in the 120 horsepower club and I'm building a 1400 cc combo for it and so this is a busy winter in my garage. The first time I was at Widman back in November of 07 there was a fella there with a 1200 Bandit sporting some kind of 4 into 1 header and the Bandit made 96 horses and 70 ft. lbs. of torque which surprized me as I thought it would be much stronger than my old Yamadog. Your original question was, did I ever get a good dyno test and yes I did, at least good enough to show me what I wanted to know. A hundred horsepower is a lot of steam for one of these old boy's, especially on Widmans dyno however it's what I got on the Interstate from 5,000 rpm up that's important for me. Of course if it was just a hundred horsepower you were after for an ego thing you could put in some big cams and some of VP's spook gas and spin up the triple digits and be done with it but you can't ride it to Chicago or Kansas City like that. What are you doing to your's and when do you plan on testing it? If you make 98.5 hp or more I'll be going back to Widman again, sooner than later and I'll make sure the print out this time is printed in the Kings English and that the graph is properly color coded. Good luck. Dan

[Elevenator]

Good enough! Thanks for the clarification.