Sorry to shift gears but I have a Yamaha TTR225 Question

[Frostbite]

Please forgive me but I honestly don't know of a better place to ask a driveability question for a Yamaha fourstroke motorcycle.

I have a 1999 Yamaha TTR-225 I used for nothing serious just some grouse hunting in the mountains in the fall and trail riding in the summer. I thought all was fine with the bike until a buddy invited me to go to a ORV park and climb some sand dune and steep trails with him and a buddy. The bike was stock at the time and would climb well initially by start missing horribly at WOT. I though huh, not enough air flow perhaps because the plugs looked good.
So I added a Big Gun pipe and it sounds really cool and the low to mid range is MUCH better but it's still bucking and farting at WOT.
So, I though maybe I threw off the air balance between the intake and the exhaust? So I added a Thunder Products adjustable low boy air filter on the side of the stock air box and tried it from all the way closed to all the way open and it still bucks at WOT.
So then I pulled the cover off the airbox and tried it to ensure I had enough airflow for the new high flow pipe. It still does it.
Ok, now I'm getting pissed.
Since it pulls well in the midrange I didn't mess with the needles but thought I'd try bumping up the mains a couple sizes to see if it helped. I went from 130 mains to 137.5 and it does the same thing.
I then added a dial a jet to the system with the thought that it might fill in any lean spots in my carbueration.

The plugs look good and I still have the problem, what now?

I suspect I'm hitting the rev limiter but without a tachometer it's just a guess. I could put a remote tach on the bike but I have no idea what RPM the rev limiter is supposed to kick in.
I know this bike was never intended to be a power house but not being able to open up the throttle really makes it tough to drive in certain situations.

Any help you could offer would be appreciated.

Frosty

 

[uofm]

bike

go to thumper talk.com

 

[maim]

check the filter on the end of the straw in the tank. i had the same sort of issue last summer with my xt350. the filter was plugging and unplugging at the higher rpms. took dealer almost 2 weeks to figure this problem out.


i had the xt225 before the xt350 and i had no problems getting it to rev right out. i always shifted it when the motor stopped pulling whitch after runnin the 350 with the tac was around 8-9000 rpm. put 18000km on that bike before i sold it and the motor was never torn down although i could tell it was gettin weak.

 

[Frostbite]

Thanks Maim!

That's a great idea I never thought of trying.

I will give it a try shortly.

Does anyone else have any ideas?

Thanks again

Frosty

 

[kmer]

fuel filter is definitely a good place to start...

how about...

loose/worn spark plug cap?
loose ground?

 

[Frostbite]

Kmer, that's a good idea too. I will check the ground for the plug wire. Hum??? I'm wondering where the ground wire is for the ground?
I bet I can find it.

Frosty

Keep the ideas coming!

Please

 

[Frostbite]

I removed the fuel petcock today to check the fuel inlet screen. The reserve pickup had some gunk (very little) on it but, the upper main fuel pickup screen was clean. I cleaned them both with carb cleaner and reinstalled.

Then I pulled the gas tank and set off and checked the contacts for the coil for the spark plug. The screw heads looked a bit corroded but all in all it looked pretty good. I removed the screws and hit the heads with a wire brush and also cleaned the contact/ground wire. I was pouring rain so I didn't get a chance to try it yet but I'm hopeful.

Thanks for the help.

Frosty

If anyone has any other ideas I'd LOVE to hear them.

 

[maim]

make shure you check the resistance on the spark plg cap as well.

 

[Frostbite]

Maim, how do I do that and what should it read? I imagine I do it on the ohms scale on my mulitmeter and measure it to ground. Am I looking for infinity?

Thanks

Frosty

 

[maim]

no it should not read infinity on the ohms scale. this # from memory so im not too shure but i think you should have around 1k at least. should be the same as a sled one of similar type. check the coil too while you have the meter out. never hurts to eliminate that as possible problem.

 

[Frostbite]

Thnaks Maim! I will check

 

[suprfst]

I would change the plugs or plug even though they seem to look good ,ive seen plugs miss at high rpms and run fine at lower rpms many times.Also put your airbox lid back on,if its any thing like my yfz 450 it really leans out the jetting.Once you get rid of popping you can take the lid off and richen up jetting.Big gun should have jetting recomendations for the pipe and with and without lid.On yfz with no lid richen up needle at least 2 clips and up main jet size 5 to 6 sizes.

 

[Frostbite]

Thanks Steve, I plan to richen the pilot to improve starting, raise the needle at least one notch and adjust the fuel screw.

My mains are up two sizes already.

Will a K&N or Unifilter help out at all? Since the stcoker is just a couple different foam sheets I can't see a lot of improvement.

Thanks again

Frosty

 

[maim]

i have a uni in my xt350 and didnt notice that much of a difference.

 

[Frostbite]

Thank Maim, you have been a lot of help.

What mods am I missing for my TTR225?

Frosty