99 TT-R 250 Mods...

[mhopton]

Hi all, I've recently bought a 99 TT-R 250 that is really a sweet bike; however, I'd like to drop the clip down a notch, open up the snorkel, and open up the canister a bit. Does anyone have any detailed instructions on the carb mod - dropping the clip to be exact?

Also, for the airbox, what have you other owners done to modify it? When you remove the seat, you see two snorkel like openings and right behind them sits an electronic control module. What exactly have you done to open it up without displacing that rubberized "black box" control module?

On the muffler, what exactly can be done around the spark arrestor to open it up and reduce some of the back pressure?

Any help would be appreciated. I did a search for this info, but only got details on replacing the entire carb, which I'd rather not do.

Thanks,
Mike:think

 

[Fergy]

mhopton,
I can only comment on the airbox modification. I removed the seat, then pulled out the rubber snorkel, leaving in place the CDI module (aka black box).
Don't mess with the CDI module for it'll cost you ~$200. With the snorkel removed from the top of the air box (just pull it out, its only glued in), use a hack saw blade to enlarge the opening. I placed an old rag over the air cleaner to collect all the plastic pieces that were displaced during the sawing operation.
This opening will allow the engine to breathe better. While I was at it I also installed a breather kit onto the top cover of the engine. Stroker Speed makes a lot of after market stuff for improving the TTR 250. This breather kit replaced the rubber hose from the valve cover to the bottom of the air box.
This breather kit was a rubber hose with a K & N air filter on the other end. This kit reduced the potential for back pressure within the engine (~$35).

As far as the carb, well I replaced it with a Mikuni 33mm from Stroker (~$350ish). Improved overall performance by ~ 30% (seat of the pants observation). Recently, I had to switch back to the stock carb, the Mikuni was acting up. Stock carb looses a little when compaired to the Mikuni, and has a noticable "pop" when off rev'ed. Even with all the mods I installed, I didn't perform any adjustments to the stock carb (like re-jetting, clip adjust).

The first thing I did to my TTR was remove and replace the exhaust system (boat anchor). Replaced it with a Stroker unit (~$200) dropped ~ 4lbs and improved performance, not to mention a better sound (more 250F-ish).

good luck,
fergy

 

[mbmotorspt]

Fergy pretty much hit the nail right on the head.;)

I have a 2002 TTR 250 that I have been riding off and on. The best thing I did was remove the stock arrestor. I had the local shop oder a 140 jet, as 137 is stock. But, just lowering the clip...raising the needle was all I needed. Obviously, check the plug before making any adjustments. In my situation the needle clip change was all that I needed to make up for the better spark arrestor.

Instead of cutting the boot out of my airbox, I just removed the entire side cover and then made an aluminum plate to cover the lower 2/3....this left about the top 1/3 open...(I messed around with it all open...half open...until I found the best combo) This way if I want to ever sell it...it won't be chopped up and I can put it back to stock with no mods.;)

Oh yeah, I also replaced the stock filter with a UNI filter.

I have really had a lot of fun with my TTR250. The front suspension is tuneable (at the bottom of the forks) and the rear is fully tuneable also.

Good luck and have fun!:)

Hey Fergy, I was thinking about going to the 33mm mikuni what's up with yours????

mb

 

[midana86]

check out subject ttr 250.


midana86

 

[Fergy]

mbmotorspt,

The Mikuni 33 that currently off the bike is ..well...being investigated further.

When I installed it a few years ago, and just up to recently, it worked just fine.
However, over the past few weeks, it started developing a loss of power/bog when pulling up a steep grade and anything above 3/4 throttle.
I thought it probably needed to be serviced, so I pulled it apart, cleaned it out, drained the bowl/jets and reassembled. Didn't help much, so I pulled it apart a couple of more times...no difference. I even took it down to the dealer to have the valves adjusted (thought that might be contributing to the problem) and discussed them them the carb(?) problem. When I went to go pick it up they indicated that the valves didn't need any adjustment and that the problem I was experiencing was probably attributed to the CDI unit.

Well to make a long story short, in my disgust I repalced the Mikuni 33 with the stock carb. I think I might have an air leak in the manifold (carb to engine) being that I was R and R-ing the carb.

fergy

 

[midana86]

fergy,

when i got my carb from stroker it had a promble.the bike would stall when
i slowed down. at first i though it was me not pulling in the clutch but dean at stroker told me 1 in 20 are bad .dont know why. seems to me 3/4 throttle
was a dog also.try adjusting the float level.

midana86:(

 

[mhopton]

I appreciate the tips... I pulled the silencer core out of the stock can last night, which was a major pain since the "gentleman" who owned the bike before me opted not to reinstall bolts using a bit o' anti-freeze. Thus, the head twised off. Even attempting to back it out using a backout bit, it was still frozen and ended up twisting the whole fixed-nut piece out of the metal lip. What a P.I.T.A.!!! With some creativity and new 6mmx12mm hex head bolts, I was able to come up with a solution that works well and holds the end cap on as good as before.

I thought for a little while that my only option was going to be to buy a stroker or Procircuit unit...

Speaking of Stroker, I am having a real difficult time locating where they are. Yahoo searches say their website is strokerspeed.com, but that site doesn't work. How bout a little more help with a phone number or a good website...?

Thanks,
mike

 

[mbmotorspt]

mh,

I installed a procircuit t-4 silencer. My local shop ordered it. It utilizes the stock head pipe and made great power gains, along with better sound and less weight for under 200 bucks.

mb

 

[Fergy]

mhopton,

Stroker has moved their site to http://strokerspeed.platinumweb.com. BUT the site is under construction. They actually moved it and its been down for some time. They can be reached at (760) 948-2871.
fergy

 

[mhopton]

mb & fergy, thanks a lot for the update on Stroker. I called, left a message and will hopefully hear back later today.

I've got the airbox and muffler under control, but can either of you give me tips/instructions on lowering the clip a notch? I'm a pretty competent shadetree mechanic, but don't have a lot of familiarity with carbs. I DO have a Yamaha service manual for this bike on the way... to the tune of 55 bucks, ouch!!! I'm sure it's worth it though, I have HELM manual's for all of my cars, past and present, and they've been great investments!

thanks again,
Mike