Attilas's Dyno Test

[Dan Hodges]

Here are my two dyno test. The one from October didn't quite make it because the clutch was slipping in the midrange but it still made 94.5 hp and 70.31 ft. lbs. of torque before the clutch gave it up. On Friday 7-18-08 sporting a new clutch I tried it again. The graph is not as clear as I would like but Widman's dyno printer wasn't very dark. The torque reading's should be divided by two and I have the correct numbers penciled in beside the really big ones. The final readings were 95.58 hp and 73.95 ft. lbs. of torque which is more torque than I expected and less hp than I wanted. I installed the intake cam at 5 degrees advanced which fattened up the torque but cost me some on the top end I believe. The carburetors are stock except for a main jet change and the air box has 3 one inch holes in the air cleaner base. I wanted a 100 hp and still think it's attainable but as of now this is what I have.

[ejoy1220]

Impressive numbers for minimal amount of modifications! Didn't they make 95bhp at the crank stock? Nice job

[Dan Hodges]

Attila on Dyno



Let's get ready to rumbleeee!!!

[81xsproject]

Is this the 1311cc motor?

[Dan Hodges]

Originally posted by 81xsproject
Is this the 1311cc motor?

No it is the 1179.

[Dan Hodges]

Originally posted by ejoy1220
Impressive numbers for minimal amount of modifications! Didn't they make 95bhp at the crank stock? Nice job

They were advertised at 95 horsepower and 66 ft.lbs. of torque at the clutch but they put about 75-80 hp to the rear wheel and maybe 60 ft.lbs. of torque. I would not say mine has a minimal amount of modifications and you might check the other post here to see what the others have made modified or otherwise. Thank's for your comment.

[Dan Hodges]

Re: Attils's Dyno Test

Originally posted by Dan Hodges
Here are my two dyno test. The one from October didn't quite make it because the clutch was slipping in the midrange but it still made 94.5 hp and 70.31 ft. lbs. of torque before the clutch gave it up. On Friday 7-18-08 sporting a new clutch I tried it again. The graph is not as clear as I would like but Widman's dyno printer wasn't very dark. The torque reading's should be divided by two and I have the correct numbers penciled in beside the really big ones. The final readings were 95.58 hp and 73.95 ft. lbs. of torque which is more torque than I expected and less hp than I wanted. I installed the intake cam at 5 degrees advanced which fattened up the torque but cost me some on the top end I believe. The carburetors are stock except for a main jet change and the air box has 3 one inch holes in the air cleaner base. I wanted a 100 hp and still think it's attainable but as of now this is what I have.

The stumble or gagging at 2500 rpm has now been corrected. Someone on Channel Eleven talked about stretching the stock slide springs 8 mm to slow down the rate of lift on the slides at off idle and I stretched mine 1/2 inch and now it has no more stumble, thank you , thank you, thank you. I have a new set of V-Max slide springs but they are 2 inches longer than the XS springs but have 26 coils vs 36 coils of the XS springs and are much stiffer, too stiff probably. I had planed on using them with 1 inch removed but now that is no longer necessary. When the weather cools off I'm going to re-degree the cams and put the intake in at 108.5 degrees vs the 104 degrees I'm using now. The cam card recommends 108.5 degrees as a starting point but suggest 104 degrees if you want more low end torque. I believe I out tricked myself by advancing the cam 5 degrees as I would trade 4 ft. lbs. of torque for 4 more horsepower. Actually the little 1179 is running good now and it's nearing the end of it's developement as I have more cubic inches, bigger carburetors, a bigger intake cam and compression on the horizon. Tomorrow is another day.

[ejoy1220]

Originally posted by Dan Hodges
They were advertised at 95 horsepower and 66 ft.lbs. of torque at the clutch but they put about 75-80 hp to the rear wheel and maybe 60 ft.lbs. of torque. I would not say mine has a minimal amount of modifications and you might check the other post here to see what the others have made modified or otherwise. Thank's for your comment.

Whoops, didn't realize you had a big bore kit!

[81xsproject]

What a coincidence, as we speak, I am going out to test out extending my slide springs. I would say that I have extended them about 5mm for the first run. Will report back. I actually have a new one ordered to measure the length and see if they have shrunk over the last 26 years.

On a side note, Dan, I thought you were opposed to using larger carbs. Not trying to stir the poop, but when Dan speaks, many (myself included) listen.

[Dan Hodges]

Slide Springs And Stuff

Ever since I put them Mega Cycle cams in my motor I had that stumble at 2500 rpm and I lowered the stock needles .025 by sanding the plastic donuts on the needles and this eliminated the 2500 rpm stumble but at 3,000 rpm and up it was so lean it would hardly run untill 4500 rpm. I tried a Dyno Jet kit installed per the directions with the needle clip two groove's from the top and it ran like sh.. and would not rev past 6500rpm. I put the carbs back stock with my Mikuni 117.5 main jets and the pilot screws out to 4 turns and the stock springs stretched 8 mm and that didn't seem to help much with the stumble at 2500 rpm but I had an appointment on this past Friday the 18th. for the dyno test and I ran that combination. The graphed showed the AF ratio totally fat from 2500 rpm to about 3200 rpm and when I got home I took the springs out and stretched them out to .750 longer than stock and that worked. I had bought a set of new springs and when I compared them to the old original ones the original ones had shortened by maybe an .125 inch which I don't believe was enough to effect it. I also bought a set of new V-Max slide springs but they are two inches longer than the XS springs and much stiffer and I had planned on using them and cutting them off a quarter inch at a time untill I found it's happy spot but that is not necessary now as I've solved the problem. Let me know how your's turns out. As far as the carburetors go, I had one of the stock 34 mm Mikuni's flowed and concluded that the 34's would be more than adequate for a motor putting a 100 horsepower to the ground and would have a better torque curve than the 36 mm Mikuni's that I have on the shelf. The 36 mm carbs would probably make 2-3 more hp on the top end but the over all power curve would not be as good. A 1300 cc motor will like the larger 36 mm carbs and will want more camshaft which is a bummer because I thought the ones I have now in the little 1179 would be suffcient but now I don't think so. All of this carburetor stuff has to do with air flow which is relative to the size of the motor, camshaft used, cylinder head flow and the rpm you turn the motor. Some of the newer carburetors with flat side diaphragms and yada yada can in some circumstances be more responsive when you whack it at low rpm but once the slides are fully raised it's strictly a matter of total air flow and of course the fuel curve. At WOT on a dyno the motor doesn't care if it has flat side vacum slides or no slides for that matter. Mention is made, all 34 mm carburetors do not have the same size venturi's, ditto for the 36's. A stick of 33 mm smooth bore race carburetors would be the plan for a hot XS but smooth bores are a pain on the street and my XS is a street bike. The early FJ 1100 36 mm Mikuni carbs even have the vacum port on the #2 carb that is applicable for the vacum advance hook up on the Eleven and they really are plug and play but are not necessary or even desirable on a 1200 cc Eleven unless you are a nut case and just have to have that last 3 hp at 7500 rpm and up however it will be at the expense of any rpm less than that. This stuff will drive you crazy if you let it.

[Dan Hodges]

Re: Slide Springs And Stuff

Originally posted by Dan Hodges
Ever since I put them Mega Cycle cams in my motor I had that stumble at 2500 rpm and I lowered the stock needles .025 by sanding the plastic donuts on the needles and this eliminated the 2500 rpm stumble but at 3,000 rpm and up it was so lean it would hardly run untill 4500 rpm. I tried a Dyno Jet kit installed per the directions with the needle clip two groove's from the top and it ran like sh.. and would not rev past 6500rpm. I put the carbs back stock with my Mikuni 117.5 main jets and the pilot screws out to 4 turns and the stock springs stretched 8 mm and that didn't seem to help much with the stumble at 2500 rpm but I had an appointment on this past Friday the 18th. for the dyno test and I ran that combination. The graphed showed the AF ratio totally fat from 2500 rpm to about 3200 rpm and when I got home I took the springs out and stretched them out to .750 longer than stock and that worked. I had bought a set of new springs and when I compared them to the old original ones the original ones had shortened by maybe an .125 inch which I don't believe was enough to effect it. I also bought a set of new V-Max slide springs but they are two inches longer than the XS springs and much stiffer and I had planned on using them and cutting them off a quarter inch at a time untill I found it's happy spot but that is not necessary now as I've solved the problem. Let me know how your's turns out. As far as the carburetors go, I had one of the stock 34 mm Mikuni's flowed and concluded that the 34's would be more than adequate for a motor putting a 100 horsepower to the ground and would have a better torque curve than the 36 mm Mikuni's that I have on the shelf. The 36 mm carbs would probably make 2-3 more hp on the top end but the over all power curve would not be as good. A 1300 cc motor will like the larger 36 mm carbs and will want more camshaft which is a bummer because I thought the ones I have now in the little 1179 would be suffcient but now I don't think so. All of this carburetor stuff has to do with air flow which is relative to the size of the motor, camshaft used, cylinder head flow and the rpm you turn the motor. Some of the newer carburetors with flat side diaphragms and yada yada can in some circumstances be more responsive when you whack it at low rpm but once the slides are fully raised it's strictly a matter of total air flow and of course the fuel curve. At WOT on a dyno the motor doesn't care if it has flat side vacum slides or no slides for that matter. Mention is made, all 34 mm carburetors do not have the same size venturi's, ditto for the 36's. A stick of 33 mm smooth bore race carburetors would be the plan for a hot XS but smooth bores are a pain on the street and my XS is a street bike. The early FJ 1100 36 mm Mikuni carbs even have the vacum port on the #2 carb that is applicable for the vacum advance hook up on the Eleven and they really are plug and play but are not necessary or even desirable on a 1200 cc Eleven unless you are a nut case and just have to have that last 3 hp at 7500 rpm and up however it will be at the expense of any rpm less than that. This stuff will drive you crazy if you let it.

Here is a pic of a V-Max slide spring clipped one inch versus a new XS spring



Everything is beautiful now.

[Dan Hodges]

Re: Re: Slide Springs And Stuff

Originally posted by Dan Hodges
Here is a pic of a V-Max slide spring clipped one inch versus a new XS spring



Everything is beautiful now.

The MegaCycle cams because of their increased duration create more vacum (draw) for the stock slide springs to control and consequently the slides were opening too quickly at 2500 rpm and causing the AF ratio to go fat and it didn't clear up untill about 3400 rpm which caused the motor to gag or stumble at WOT in 5th. and 4th. gear at 2500 rpm. At about 4500 rpm it got slightly fat again. Stretching the stock springs worked initially but within a couple days it was doing the same thing again. On disasembly, I found that the stretched stock springs had sagged (settled) back down to within a quarter inch of what they had been before I stretched them. You could reduce the size of the vacum hole in the slides to achieve the same results as using the stiffer springs but the springs are a simpler deal. I nipped one inch off the V-Max springs and it cured the problem. Getting the low end drivability response on this thing with those cams and the CV carbs have been a real pain but all is well that ends well. It seems there is scads of information about this stuff pertaining to Kaws, Susuki's and even 750-1100F Honda's but when you do it to an XS it's strictly trial, error and lot's of patience. I now have a shoe box full of slide springs in case one goes soft, a most terrible thing to have happen, to an XS.

[81xsproject]

This is all good info. The one thing that I wanted to add, and I am not sure if you noticed it or not Dan, is that stretching the slide spring caused a noticeable negative effect on throttle response. The stiffer springs created a delay on quick throttle snaps.

I can't yet afford new cams, so once I get the MS system in and operating, I am going to put the 70's cams in.

[xschop]

EVIL EYE

I'VE BEEN WATCHING TOO!.....Things are starting to make sense between this post and AE7F's post on the ZRX carbs. I was thinking that his ZRX carb springs are meant for the airflow of the 1200 cc, 4 valve motor (he said he has low end stumble). I just got a set of those for the Big bore, and now I don't have to jack with trying to match my perfect running XS carbs to the 1196 kit that is coming, just slap them on my low mileage motor I have in storage....Great thread and good work.....chop

[Dan Hodges]

Originally posted by 81xsproject
This is all good info. The one thing that I wanted to add, and I am not sure if you noticed it or not Dan, is that stretching the slide spring caused a noticeable negative effect on throttle response. The stiffer springs created a delay on quick throttle snaps.

I can't yet afford new cams, so once I get the MS system in and operating, I am going to put the 70's cams in.

Stiffer slide springs or smaller lift holes does slow the lift of the slides down given the same amount of vacum pulling against them however the aftermarket cams are making more vacum but unfortunately I don't know how much more nor is there anyway of telling how fast they are opening as you are unable to look at them while the motor is running. Obviously the quicker you can lift the slides without the thing going fat at low speed the better because the slides plug up the venturi and limit air flow untill they are fully open. The DynoJet needles for the XS are longer than the stock needles and have a more gradual taper and I tried them per instructions with the needles two clicks from the top but with that setting it was so lean it would hardly pull 5500 rpm. I think I might try the DJ needles again with the stock springs with the needles two clicks from the bottom. My mission is to get rid of the 2500 rpm stumbles when you wack the throttles to WOT with as quick of slide lift as I can come up with. It is worth repeating that with the 78-79 cams I did not have this problem however I will get it right eventually. You could I suppose do a dyno test, look at the results and make the corrections there if they would give you a place to work however I prefer to work on it in my garage where my tools are and where I can be alone and think. Secondly and most importantly, running it to death on the dyno isn't necessary and is hard on the bike. I have attached a picture of the DJ needles next to the stock ones and you can tell what the difference is. The DJ kit is designed for 80-81 Specials and Standards and the 82 XJ and of course all three of those models have much different carb's, particully the XJ with the air injector system (YICS) of course you cannot explain that to DJ. At the moment it runs good on the bottom however I agree that the stiff springs are probably slowing the slides down too much for optimum performance but I don't know that for sure and so the testing continues. Thanks for the imput. Oh yes, I'm doing this stuff myself rather than hiring it done because nobody would have the patience I do nor would I trust them. Thanks again. Dan