11 replies to this topic
  • mat

Posted November 30, 2001 - 02:28 AM


anyone have the website address for the company that makes this?

  • crazyadam

Posted November 30, 2001 - 03:52 AM


I don't think that Factory R&D has a site, but www.mxsouth.com/perp38lit.htm has a picture, sells around 75$.
from my research... I am saving the $ and doing the Brian Kinney mod. which is adjustable.

  • Rusty

Posted November 30, 2001 - 04:54 AM


From what I understand Crazyadam......is that from 2000 model on there is an ear (part of the mold on carb body) that allows you to perform the BK mod. The additonal material allows you to drill/tap and use the screw/springs etc. to do the mod. On 98 and 99 model years (mine's a 98) the extra tab or ear isn't there which means we can't do the BK mod per se. There was also a post showing an alternate means of doing this (on this board) on the 98s & 98s but it entails drilling a hole in the accelerator pump (I believe) cover and this makes me really nervous. This is just the information I was looking for. The only shortcoming is that ours wouldn't be adjustable but I can live with that. Thanks very much for putting up the link. I'll be ordering mine soon. I hope it lives up to all the positive comments on this board. Correct me if I'm wrong anybody.

  • Boomer

Posted December 01, 2001 - 03:34 AM


I have a 2000 - DO NOT pay for the P38

it's absolutely not worth it.


  • speedharris

Posted December 01, 2001 - 04:20 AM


I'm going to try the Mod for the older carbs first, because if I distroy my cover, it's only about $27.00 at Riva Yamaha. They have an online fiche page. I've also seen on this post that there is another Co. selling the cover for $17.00. This souldn't make you too nervous.
Well, I hope this helps.

  • Rusty

Posted December 01, 2001 - 04:40 AM


O.K. Boomer now I'm really confused. I wrote a private message to another individual from this board that did the p-38 and he pretty much raved on it. I'm not doubting your post and I appreciate the information, however I have to wonder how two people can have totally opposite opinions regarding this mod. You're saying that it didn't do anything at all for ya? Can you elaborate some?

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  • Boomer

Posted December 05, 2001 - 01:32 AM


Hey Rusty - how's the weather holding out in in my favorite state? I've been trying to find a Sales job there for about 2 years - need to relocate in AZ!!!!!!!!!

My 2000 is probably the worst case of caughing / hiccuping / stumbling Yamaha produced!!! I am dead serious. I was almost thrown over the bars repeatedly, even on flat ground coming out of 90 degree turns. Any attempt to wick open the throttle just made the engine completely cut out. I once landed face side of a double, managing to stay on the bike, but injuring my shoulder.

I took the bike back to the dealership, they did not have clue - they called Yamaha who completely denied any carb problems - they must NOT read TT. I was on my own from that point on.

I messed with the carb for a couple weeks, then saw the ad on the P38 - I called Factory who told me the P38 was THE ANSWER to the problem. The P38 is not the answer - my bike still caughs (maybe a tiny bit less often, but that could be attributed to the bike being almost broken in). I don't trust the bike - which makes me ride slower than I normally would. Jumps are not all that much fun on a bike that you know could go nose down. I have a family to take care of.

So, the answer to your question is "maybe because my bike has a major carb flaw", I haven't obtained results near what some other guy's bikes are getting.

I'm contemplating the BK mod, but my motor has a ticking noise inside. I believe it is from a bent shiftfork. If it is, I'm ditching the bike. **** -this thing is over 2 years old and still on the original tires and chain & sprockets. Can you say new???????

I'm not paying any dealership $2,000 to do a rebuild when the bike should be bullet proof.
For me, it is just a matter of time before I decide to dump the bike instead of incurring major dollars due to catastophic engine failure.

As you can tell, dis-service by Yamaha has made me sour - I just sold my 86 FJ12 because of Yamaha's crap - I have 2 Yamaha's left to sell, then I'll be done with them.

Too many guys have been left hanging by Yamaha - this bike has inherent design flaws. Check the threads for hubs, transmissions, carbs, and clutches -- You'll see what I mean.

Sorry to spill it all here - good luck with your bike....


  • Boomer

Posted December 05, 2001 - 01:42 AM


Rusty - BTW - On the upside.....

I have been (was) a Yamaha only guy since 1972 - it's too bad that Yamaha has choosen the "ignore them and they'll go away" additude.

The 426 has HUGE potential. I fell in love with mine the moment I swung a leg over it the first time. In my opinion, the bike has great straight line tracking, awesome power, nice corner carving characteristics. It handles really well.

Several guys have postaed things they would like to see Yamaha address on the bike, and I think Yamaha will. Yamaha has always lead in the release of technology. Others always play copy / catch-up, then Yamaha ups the ante again. 2003/2004 will be an interesting year for Yamaha tech again.

A lightweight 426/450 would be nice, but not at the expense of durability - and certainly not for $6000 plus.



  • yzernie

Posted December 05, 2001 - 07:23 AM



Did you rejet after installing the P-38??? If you didn't, that is what is causing your problems. Need to go richer on the pilot to compensate for the shortened pump squirt.


  • MN_Kevin

Posted December 05, 2001 - 09:08 AM


See my instructions for the JK (or KL) mod for 98/99's. There is ZERO to be afraid of!! :)


This works like a charm! If you hose up the cover, I think it is less than $20.00.

As long as you have acces to a drill press (or a brutal steady hand) you are fat (fat, dumb and happy! :D )

  • Fastest1

Posted December 05, 2001 - 09:56 AM


So it is all Yamaha's fault? All the rest of us are pretty happy with our Yamaha's! They seem to run very hard as evidenced by their wins. I was bleeding Red (Honda) only for years. They didnt build a 4 stroke mx bike quick enough. As far as who leads the technology I always thought it was Honda (I still do think that). Honda's finish on welds and build quality is superior to any of the rice burners. These bikes are race bikes, parts need to be replaced regularly. As far as hubs and things breaking how were they treated? I weigh 255lbs. I jump plenty but I dont treat my bike brutally. It has held up good. Weight is generally the reason for failure cause we all want lighter shi*! Dont mean to totally bash you but it was time to sell the 86 FJ anyway. That is the bike you should have been upset with! Try an R1. Cya :)

  • Rusty

Posted December 05, 2001 - 04:16 PM


Wow all kindsa information. Thanks Boomer for the elaboration. It's a shame that you've had such bad luck with your bike. In Yamaha's defense though, every once in a while somebody's gonna get a lemon. When you crank out as many units as they do, one's bound to slip by sometime. My problem is not nearly as severe as yours sounds. It's almost to the point where I think I should leave it alone. It starts fine and the hesitation is barely perceptable. I don't race (just recreational desert riding). Maybe that's why I don't notice it so much. NH Kevin I read all your information (kinda wish it had some pics to look at) I seem to absorb images better than text. I don't have easy access to a drill press and although I'm pretty fair with hand tools I'm not sure I'd want to try it. It does sound like rejetting is a necessary evil following the mod. Maybe that was the trouble Boomer? Can't go back and look now but, did someone post that the p-38 worked for them after being rejetted?

P.S. Weather in Arizona is great right now. Probably around 68 degrees and it rained almost all day yesterday. Maximum traction tomorrow and hopefully this weekend too!

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