New Exhaust, New Jetting & Rev Limiter Woes

13 replies to this topic
  • The_Missile

Posted February 07, 2002 - 11:13 PM


I think I am now satisfied with my jetting ....I put on a new Stroker exhaust and FMF PB header and rejetted for that .... but I am having a problem as follows....

I'm running 13-53 gearing ... performance feels great in all gears except in gears 1 2 and 3 it feels like I am hitting the rev limiter very (too) quickly, far more quickly than when I had my stock header and exhaust. 4'th gear not so much and 5'th gear can't get there.

Because the pipe is quite loud I can't hear the engine revs like I used to and I have no speedo at the moment so I have no idea of what speed I am going - makes it hard to know whats going on!

I changed to 14-53 gearing and the problem has reduced somewhat.

Am I nuts or do other people have this problem ?
I'm guessing the header/pipe allows the engine to spin faster than with stock and this is just enough to start this problem.

[ February 08, 2002: Message edited by: The Missile ]

  • sbohanon

Posted February 08, 2002 - 01:32 AM


first and second gear on a wr are already very low. changing the final ratio even for tight woods should not be necessary on a wr. what you did was like putting a 4.56:1 gear ratio in a truck with 26" diameter tires!

  • MN_Kevin

Posted February 08, 2002 - 02:23 AM


Missle, I too have an extremely low rev limiter now ~ 7000rpm. I have gone lean and rich to no avail on my main jet...

I have been chasing this oddity for some time now. Maybe an E-Mail to Stroker, or is there website still down? :)

From reading the carb technical writing found on this websight (what is his name again?) , I THINK it appears my main air jet is too large. What are you runing for your MAJ??

[ February 08, 2002: Message edited by: NH Kevin ]

  • mcarp

Posted February 08, 2002 - 06:30 AM


Sounds normal to me. When the WR is modified like a YZ (timing, jets, pipe) it does rev very quickly. Your gearing is exaccerbating this problem. I can hit the rev limiter very quickly if I hold the throttle open (13/49 or 13/50). It will sound like an electrical problem where the engine cuts out and refires at the rate of about 10 times per second. You'll feel it too, especially if you stand up.

Remember the WR's rev limiter is about 1.2K rpms lower than a YZ, so you'l hit the redline a litle faster. That's fine with me, overrevving this bike would probably shave off years of life anyway.

Hey Kevin, did you ever get the cyl/piston inspected? I'm convinced you have some blow by/lower compression by the way your bike ran.
It ran clean, smooth with no obvious jeting problems, but the meaty grunt just wasn't there.
Can you stand on the kickstarter at TDC and hold it there for 20-30 seconds? Or does it blow past TDC?

  • Jason_Pettis

Posted February 08, 2002 - 05:46 PM


i seem to be having the same deal going on on my suzuki. it hits the limiter very quickly. i havent had a good chance to sort out my jetting yet, but i saw this post and it got me thinking. is there a tachometer that could be stuck on a bike while you ripped it up and down the road? it would sure be a final answer to the limiter sound that mine is making.


  • The_Missile

Posted February 10, 2002 - 11:52 AM


I think my new jetting and new pipe is the cause...a VERY fast revving engine. I cant ride the 13/53 combo anymore because of this whereas with stock jetting, pipe and WR timing it was NOT a problem. Switched to 14/53 and the bike is PERFECT. I went for my usual 4 hour woods ride and although rarely get the chance to really ride fast I never got to the rev-limiter! The bike performed flawlessly.

I think my problem was also that I was road testing when I hot the limiter and this just doesnt match with off-road style of engine use.

  • Taffy

Posted February 10, 2002 - 11:53 PM


the missile

you've done really well and everyone who reads this thread should remember that "the missile" is the only person who sat there and said "i'm going the whole hog, not half a job, not 3/4 of a job-THE WHOLE HOG".

so come on you bugger and admit that once or twice you strayed!

also tell everyone the one about revving it on the stand!

there was one other one i said that you really must do; "if you're going to check the MJ/MAJ you must make sure you're pulling valid gearing at about 14/50 minimum". 'nuff said?

as for you kevin? beyond redemption i feel!!!

missile what is your present jetting?

the point is, i never put a pipe on mine as you know so you did this one for yourself, really, really well done. jason has been doing the same over on the suzuki side. it's not easy. if you're a petrol head like me, this is one of the few good articles to come out since christmas. we've got more in common with yves st laurant than wolf nowadays.

all together lads;


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  • The_Missile

Posted February 11, 2002 - 01:35 AM


Taffy, thanks for your help and pointers along the way with the pipe....its all your work really...the jetting is in my signature but here again for clarity.

MJ 158
MAJ 160
PJ 38
PAJ 55
Fuel Screw Approx 1.5 -2.0
60 Starter Jet

The bike revs like crazy, has oodles of power across the band and pops very slightly on decel, never backfiring until I run out of gas and have to switch the reserve on.

Starting so far on first or second kick now I have stopped fiddling with the carb.

Now I have the 14-53 gearing in there I may fiddle with the clip again as I was being thrown off course by the rev limiter thing, but I am happy with clip #2 for the moment.

I fouled a couple of plugs along the way, I was suspecting the needle diameter but it was probably an 85, yes eighty five, start jet that some &%ç*er put in there. However, I have a feeling I may still be just a little rich on the needle diameter which may be being compensated by a slightly small PJ.

I may get myself an EKN, EKP needles to see if there is a slightly better solution along with a 40 PAJ to see if things are somewhat better. But I think I have just about had it with oiking the carb off, especially if the whole system leans off a little as the warmer weather approaches.

I just hope that the Swiss Motorcycle Association doesnt say my bike is too loud now...I'm entering the Swiss national championship....not that I am that 'good' its just if I want to race these are the only races organised!

Anyone know how loud a Spark Arrested Stroker SX-1 is ?

I now need a NEW project to keep me busy. I haven't had the back end of the bike off yet to look at the shape the bearings are in..........

  • Taffy

Posted February 11, 2002 - 05:14 AM


looking at your jetting and remembering where i finished i would say the following;

MJ; i thought that i might need a 148MJ but never tested it. so if 150 is good and you have the pipe 158MJ is either right or a smidge LEAN so try 160/162 one day.

your needle is either spot on or lean. if you raise it one and it gathers speed better in 5th gear roll-on you'll know!

your pilot screw could go in a little and if you do lift the needle it will make the bottom end richer so that 55/38 should go back to 45/35. however due to the pipe you're in new country.

tried the EKP. forget it. i've tried it in three times and everytime you go to pull off it causes a flat spot. it also takes an extra kick to start it. the EKN, EMN, ELN if they make 'em will be a better bet.

i bet you get told by the swizz to dump that pipe!



Posted February 11, 2002 - 06:11 AM


Dude, Get the EKN needle and start on clip #3. It works great and will fatten up 1st and second sufficiently. with the 13/53 and the pipe you'll just need to learn to short shift those two gears. I don't even use 1st with my 13/53. Snap wheelies are awesome with the EKN needle.

Bonzai :)

  • Jason_Pettis

Posted February 11, 2002 - 05:30 PM


hey, you guys all run alot different gearing than us yellow people (i have a DRZ400..sorry!)

but im not all that much into following suite (jetting like you works great) so if i go from 14/47 to a 14/50something what is it going to do for me?

i can say right now that mine blows the tire away and hits the limiter so easy in 1st that i cant even use it with 14/47.

im just a little concerned that my 'zuk wont pull the kind of gearing you guys can cause the engine is more mellow...although i guess im spinning the tire now so i need something different.


btw taffy, i have gotten pretty happy with my carb setup and have come to the conclusion that the miss i am having is for sure the limiter, like i said it hits it way easy now in the lower gears.

  • The_Missile

Posted February 12, 2002 - 12:12 AM


I would say change your gearing if you cant use 1'st gear. Its there for a purpose.
I guess to some extent it depends on your riding. I do a lot of woods, slowish steep climbs with mud & leaves ...I live in the mountains. I need the low gear and I also need to have complete control over it - as soon as I get wheel spin I dont go anywhere. Its a fine line. Higher gearing will attenuate the wheel-spin issue.
I am very happy with my move from 13/53 to 14/53.

  • Taffy

Posted February 12, 2002 - 12:28 AM


i never thought we'd end up talking gearing but here we go.

the yams suffer from a weak bottom end so it's important that the gearing is high so that they pick up quickly. also we don't want to keep changing gear by being in that weak range of revs.

the suzuki is well known for it's bottom end oommpphh! so we don't have to gear down. with good torque it will pull another three teeth off the rear and when it runs out of breath it will be so fast you needn't worry. the top speed will be there due to the low gearing and not the revs.

i can't understand why anyone would run 13/53 though because the bike is revving w/o moving forward, if at the same time you don't even use first well.....!!! it's silly.

as long as it'll pick up crisply from the bottom you should take the gearing to 14/53 or like me 14/48. with this gearing the bike didn't break traction and i did few gear changes. fuel economy? wow! try 2.5 gallons in three straight hours!

you can't run low gearing until you've sharpened up the bottom end so that it doesn't bog.

most of the riders on this site run about 13/50 average and have a rich bottom end that won't rev. if they had my gearing of 15/48 that i often ran in the summer you could put an hour glass on the time it took the bikes to rev. those of us with crisp bottom ends (missile) should be looking not to break traction out of corners by going to at least 14/48.

it's difficult to explain to some air heads that you are thinking two moves ahead. sharp bottom end means taller gearing, which saves the riders strength, which helps him ride faster longer, which means he doesn't come in for fuel, which means he's faster. oops! that's six moves ahead sorry!



Posted February 12, 2002 - 04:23 AM


Having run 13/53 gearing for the past year I must differ with you're analogy. I have raced this gear setup successfully. Additionally it makes 4th and 5th gears very usable in the woods. I don't get smoked anymore by 2 smokes in the tight stuff. Running out in the open WFO, I'm still out there hanging with the 426's and the 450's. Hill Climbing...hell nobody can touch it...3rd gear straight to the top with NO Bog....

Why would you think that the 13/53 would wear someone out. On the contrary the lower gearing makes it easier to blip the throttle and swing the lead sled around on a dime and give up 9 cents change. The front wheel lofts just by thinking about it. Downed trees and obstacles, No Problem.

The ONLY downside to the 13/53 gearing is that yes you hit the rev limiter early and 1st gear doesn't need to be used as often. It is still usable but you need to short shift it to stay off the limiter. On the MX track 13/53 is DA Bomb! Instead of hitting big doubles and tabletops in 3rd gear pinned, I can hit them in 4th Gear pinned and clear the landing zones without much effort. Digging out of the corners and whoops is much easier and the power is much more controllable. 13/53 gearing is not for everyone and takes a bit of getting used to...Took me 4 good rides to become comfortable with it. The 14/53 is also great gearing and the main difference between the two is that 1st gear is a must and it keeps you off the rev limiter just a little longer. You won't however win any dogfights in the corners against a YZ 426 with it.

Bonzai :)


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