shudder at 4000 rpm

[underdog57]

I would not write off idle mixture screws

[HobbyMan]

Either I didn't read it or it wasn't posted. What exhaust do you have. you said it was new?

[fredintoon]

You know what to do

raqumup sez:-
So anyway I got it all together and rode it WITHOUT the bottom half of the air box on it and WOW the bike is so much faster and extremely smooth I figured it was the rebuild that fixed it. Now I believe that my bike could do a wheelie if I wanted to, don’t worry I have no desire to. So brought it back to my shop and put the air filter and air box on and the side covers and was going to ride it home and when I got on the road I hit the throttle and it rides like it used to, same shudder and it did not have the power it had without the air filter. I have a K and N replacement air filter (drop in) it is clean but it has done this since I bought the bike. I bought the new K & N filter shortly after getting the bike. I was wondering if anyone else has had this problem and what hey had done to fix it. I was going to go with the 4 pod filters but I have read that some people have had problems with certain brand filters and too much restriction, so what brand pod filters have the best flow, because all I can gather is I have too much air restriction with the stock air box.
Hi raqumup,
so lose the stock airbox. I had no problem with mine except for all the knuckle-busting getting the carbs off but it had the stock air filter, not a K & N replacement. Lord, the room there is to install in-line fuel filters and swoopy unkinked fuel lines without that great coffin of a thing being there getting in the way. I fitted four UNIpods and upsized the main jets to the next bigger ones. Took my first long ride on Saturday and the old rig runs like a train.
Fred Hill, S'toon.

[mro]

are true K&N knock-offs

mro

[raqumup]

Hobbyman, its a MAC exaust dual exaust (2 to 1)

[TopCatGr58]

Originally posted by raqumup
it still needs to be tuned properly but i had it tuned at a shop by a guy who knos this bike verywell and he was not able to get rid of the shudder either ( this was several years ago) he could not get the plugs to stop showing signs of rich condition, after he gave it back to me when i would engine brake and then accelerate it would back fire like someone shooting a shotgun right behind my head, so i richend it up a bit and that stoped the backfireing but it has always run rich. i just dont get why with the airbox off it runs perfect, thats why i want to go to the pods, for less restriction.

Hey Raqumup,

I'm with Fred, in that I put on Indy filters and have had no problem with tuning carbs. I have a 4-1 exhaust system. I had purchased the el cheapo Emgo brand of CONE style Indys from BikeBandit, and they had the prominent lip on the inside mounting edge, but I didn't experience the reduced performance, or lagging/ bogging that can occur at higher rpms IF they cause an air flow restriction. But I went ahead and made some cheap velocity stack style mounts from parts from LOWES, I'll find that thread and post a link. BTW, before these cones, I had the UNIfilter pods, they are cylindrical foam filters with flat chrome caps, also worked very well, no restrictive lip on mounting flange, but not as pretty as the cone style, I have photos also I can post of both installed for comparison.

Okay, your mech tuned it "SEVERAL YEARS AGO", and it still was rich? What other work was done on the carbs? Did your mech clean them, and put in new jets from a carb kit?? K&L brand kits are notorious for improperly sized/styled pilot jets that ran too rich causing similar problem you're having. You have 4-2 exhaust, so that flows a little more than stock which should help with richness.

You said you richened it up....HOW? Lowering float levels, raising slide needle, turning pilot screws out more turns?? With aftermarket pipes, and during decel/engine braking it's normal to get some mild popping due to leaning the air flow coming into the engine when you shut the carb throttle plates, but it shouldn't give a big backfire. You may need to do some other tuning, like cam chain tensioner, valve shim clearance? Also, is your timing plate moving freely without sticking, the vacuum advance piston moving easily, yet holding position when constant vacuum applied to vacuum hose, and hose connected to #2 carb body port, not intake boot synch port?
T.C.

[TopCatGr58]

Okay, here are a couple of threads with photos on pod filters, velocity stacks, etc.!

UNIPOD filters and velocity stacks from OEM box .

Discussion about Cone Pod filters and LOWES velocity stack fix .

T.C.

[HobbyMan]

If you changd from your stock exhaust there may be some jetting issues from that swap It is definitaly jetted too rich for your current setup with the airbox

[raqumup]

I am going to get the APEraceparts pod filters and then I will spend some time tuning it, I have always hated the air box anyway and I have wanted to do these pod filters for awhile but a lot of the stuff I had read on this sight said don't get the pod filters. Well now I have spoke to lots of people that have had luck with them so I am going to get them now. Hopefully I will have them by this weekend and I will spend all day tuning it if I have to. Oh and I just richened the mixture screw a little and it never backfired again, not even the little bit you say is normal. With my 4-2 exhaust and the pod air filters, what pilot and main jets do you think I should have installed? This weekend I am pulling the carbs. to see what is in there. I know that I did use K&L rebuild kits. is the only thing bad in those kits the main and pilot jets? Or just the main? Or any other part of the kit? I can sill get the jets from Yamaha correct? thanks for the help guys, I really appreciate it.
Troy

[raqumup]

hey topcat
the links you posted, it says i don't have permission to look at them. i don't know why

[fredintoon]

raqumup sez:-
hey topcat
the links you posted, it says i don't have permission to look at them. i don't know why.
Yeah, me too. Arrogant stupid link. WTF?
That does it! Be damned if I post my baby pictures now!
Fred Hill, S'toon.

[TopCatGr58]

Hey Fred and Troy,

Relax, I had thought I had just copied them into the Tips Under Construction section, but the site apparently MOVED them instead, and so that's why only Mods are allowed to view the Tips Under Construction.

I've recopied them back into the XS-XJ tech forum, and fixed the links, will allow you to view them now, but hopefully I'll be able to get them cleaned up to save as a tech tip, so they will be easier to find next time!!
T.C.

[raqumup]

yea they work now, thanks
well when i get my new filters and try to tune it i will let you know how it turns out.

[raqumup]

SWEET

I love the new filters. Did anyone else have trouble with them slipping off during installation? As far as I can tell because of all the different bikes it can fit, some it probably fits perfect but mine they had to stretch to fit over the carb. and with no grove in the rubber for the clamp if you don't get it just right it slips off. This scared me in the sense of what if they pop off while riding, I will loose them, so I had to come up with a retaining system. I drilled a small hole in the lip of the chrome cap (not interfering with the filter at all) and safety wired them to the bike. So if it does fall off I will still have it. but anyway I spent a little time on Friday tuning the bike and my shudder at 5000-5500 is gone so I guess the stock air box was the problem the whole time. I still had a spun crank bearing and replaced 2nd gear so the rebuild was not a waste. But thank you all for all your advise. I posted another thread called exhaust temp.? If any one has any answers on that subject please read that tread.
Thanks again
Troy

[raqumup]

sucks

it is backfireing now really badly. i went to a local bike shop and a really nice machanic helped me out and based on my description of what the bike is doing he sugeted to go with bigger main jets. i had 137.5 mains 180 pilots in all of them the only thing they had was 147.5 mains so he traded them for me and now the shudder is back and it still backfires like it is still too lean. i think my carbs are junk maby i shoud get some different ones. i don't know. this bike is making me loose my mind.