125-200cc 99 WR125 needs another teaspoon of torque!

Whats it gonna take besides a 165 kit? I finally got this thing in the muddy, rocky, mountain woods and the hills/rocks were a nightmare. I knew it would be bad, and I'm a 4t guy for a looong time too besides. Anyway, I don't want the 165 kit, though for this application it would make sense.

I'm thinking maybe a PV spring, adding a base gasket or even some porting if I must to build a little bottom/mid before the valve opens and it just spins the tire. What options are there that will add some meat down low but not lose the MX ability of the bike. I'm looking to smooth the hit and extend the power a little lower, but not move it all to the basement.

Thanks!

The best mod for that vintage WR125, is a DynoPort pipe. Rich Daly still has the jig and will build you one.

52t rear sprocket - CR ignition ( with FWW ) - Fatty - 144 kit .. in that order
Silver/small pv spring does help a little bit too

Youve found out why the 165 kit is popular

Cr ignition will not add torque but will ensure there is more momentum - response - no bog

I'm not really feeling a bog, it has a PC pipe/silencer on it too BTW. I dropped the gearing to 13/51, I was thinking another tooth out back but didn't want to bring the hit in that much faster too. There is a thin slice of torque just above idle and before the hit that isn't terrible, respectfully. Just below that slice it barely keeps running LOL! Then it hits and it all goes up in tire spin.

I'd like to just make that slice of torque wider & a little deeper.

If this was all I did with this bike, and it was my only bike, the 165 would be a no brainer.

Thanks guys, maybe I'll go grab that 52 tomorrow. $ isn't there for a new pipe, my EXC engine is going to 610cc!!!

If you can find an old fatty its worth a try - I had a procircuit on my 06 and didnt find it much better than standard - only on top
The spring ? Or try adjusting power valve arm bolt close to top - may be worth a try .

I guess a heavier spring will delay the PV? I'll take a look at the arm too and watch for a clean used fatty, thanks.

Walts' guide to PV springs might help zero in. Theres a meriad of combinations.

I think your only spring help will be to add an inner spring to slow the opening so you get a more manageable transition to the pipe. Bottom line is that a 125 only makes so much bottom and still rip on top. I also think the 144 might be your best option as it retains 125 like powerband but develops much more bottom/mid.

Thanks Wally, I was just reading your threads about PV springs and adjustments.

I know there isn't much there, and I wasn't expecting to find much more easily, but even just a little would be much better, LOL. What would a doubled up base gasket do? I'm not very good with port heights and the effects changing them makes. Would the lower compression & higher ports send me in the right direction? Pump gas BTW.

Is that kick in the ass HP boost the PV opening up fully or the engine just hitting the sweet spot of the porting/torque and HP?

Thanks, Jim

Ah, the opposite effect!

A thicker gasket will raise the ports which increases exhaust port timing. This will give more top end and less low end. The same thickness should be removed from the cylinder head to keep the compression the same as stock. A thinner gasket will decrease exhaust timing which will give less top end and more low and midrange power. Piston to head clearance should be checked to be sure there is at least .020" inch clearance.

So a thinner base gasket might be OK but I'd need to confirm squish. Is this a common practice on these bikes?

You can get the head machined for around 75 - RB ? designs look in index - for better squish band
saves pulling off cylinder

Extra silver or blue Inner pV spring helps to delay power valve opening and helps mid range

Guy who has my '02 WR125, uses it as his ECEA Rock Run enduro bike. For me it always was a torque monster with. 13/52 gearing, carb divider and DynoPort pipe. Only difference to your '99 is.... '02 has CR tranny and V Force reed block stock.

Thanks Norman, I'll give the 52t a try first, then maybe even the stock pipe too. I can't dump a bunch into it, I already did the suspension up right and a few bits here & there.

You could be on to something with the pipe
Ive seen tests on pipeswhere they gain on top but lose some down low
A 12t front is a cheaper sprocket option
Another option to consider is a cheap secondhand keihin 36mm PWK
They came on a lot of kx and Rm 125s in the 90s

Yes, but a 12 is a pretty big jump and I still want to track this thing and it is slightly short for that now. I think it has perfect HS gearing for NJ now, but maybe I will try a 12 and just swap the CS when I need to. Then again, I felt like I was stuck between gears in 1st and 2nd a few times today... That one tooth out back might just make the difference.

The PC really enhanced the snap and rev, it had the stock pipe and very restrictive OEM silencer that I de-sparkied, but it just barely moved at the bottom of the RPMs. Like it was hard to get it to even roll away from the truck at the track.

I have a friend with a worked over TMXX that he isn't using, maybe I'll try that for a ride too.

I would go with high compression

I'm in NJ with that very bike. Actually, it ran very soft at the Ridge Run last sunday...I think I jetted it too lean and it would not pull on the pipe w/o bogging. it would pull hard for a sec or 2 then fall flat. I also added .2mm on the base gasket to combat some detonation I was having with 100 octane fuel on my EG 144 kit. The detonation is gone and so is the rip so I might put it back and run more race gas.

Anyway...I'll get it sorted and then you can take it for a spin if you want.

BTW my 04 CR125 with an FBF 135 flys too.

One think to keep in mind...the Mikuni carbs on these bikes are VERY sensitive to jetting.

One day they can rip...the next day..nothing.

The Kihein carb helps with that.