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I found a TT350 this last summer and bought it fairly right. The bike over all is in good shape, but it does need engine work. Is the XT motor identical, and did they make any XT350's that were electric start ?

Looks like the TT may have a little better quality suspension too.

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I owned both. The TT350 is the same basic motor as the XT350. The TT had a different cam that moved the power band up in the rev range. One flaw in both bikes was the intake boots which would crack and leak air. Only good alternative was to buy new ones.

 

Neither bike ever had E start in the US. An XT350 with the TT suspension (and E start) would make a fine DS bike.

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Thanks Glenn, that's kinda what I thought. I've been watching eBay for parts for XT's and TT's it doesn't look like there's a lot of stuff kicking around. Not sure what I will end up doing with the bike. Had a guy in the area with an 89 XT that looked immaculate for sale, he wanted top dollar though. Claimed 200 mls on the bike. This would've of been a great parts bike.

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  • 2 weeks later...

There are other differences in the tt350/tt250 (aus only) and the xt350 engine but there all upgradeable to tt standard.

 

the tt350 and tt250 suspension and frame is simply light years ahead of the xt version, its a totally different setup, the xt does not even come close,  the tt350 had some of the best suspension out there at the time i think its way better than my 2004 xr400 in stock trim.

 

I did not know about the more aggressive cam, my research shows that this is simply not true there the same part numbers and the same cam for both intake and exhaust. What gave the tt350 a significant HP boost over the xt350 is the jetting and setup of the carburettor. I would change out any xt350 jets for the larger tt350 ones for more power and to make the bike run cooler. it also has a diffrent rotor that could be lighter than the xt350 one but that is just a guess i know its diffrent just not how.

 

In the bottom end the tt350 has a different clutch basket that takes two more plates really improving the clutch a lot. Also the tt350 has a brass oil pump gear not the nylon crap found in the xt350 and the tt250 (aus only). The nylon oil pump gear wears out in about 30,000 km and kills the engine in these bikes if it’s not changed. You can swap a tt350 clutch into a xt350 but you also have to swap the oil pump over aswell as its driven off of the clutch basket and will not work if there miss matched. OEM parts are still available through partzilla and Yamaha for the xt350 and tt350. Most parts from the xt350 will be available and work perfectly in the tt350. The tt350 while only sold in the states for two years 86 and 87 if i remember rightly was still sold in Australia until at least 1991. They are a fantastic bike with some sweet features and simply shit all over the xr of the same vintage.

 

http://www.partzilla.com/parts/search/Yamaha/Motorcycle/1987/TT350T/parts.html

 

All This info is from my personal experience with these engines and bikes, I have both the tt350 and tt250 in the shed and have played around with the clutch mod for the tt250 (same bottom end as the xt350).

 

It’s a good bike to rebuild really there cheap to buy and there are plenty of new and used parts around for them if you include the xt350 engine parts as well and when there done you have a great bike that is a really excellent and reliable machine.

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If I do not tackle this bike as a winter project and make a runner out if it, I was going to consider looking for an older XR400 for a plate-able trail bike. It's interesting to hear that you felt the TT was a potentially better bike.

I do tend to be a Yamaha fan especially for dirt toys. I have two IT200's that I may move on to a new owner if I proceed with the project.

Thanks for the input.

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If I recall, the cylinder heads are different between USA XT350s and TT350s, even though the engines look identical from the outside.

I think the intake valves and intake ports are smaller on the XT.

 

I have owned a 2000 XT-350M and a buddy of mine owned a 1987 TT350T back in the day, and I recall no situation of the actual powerband being moved up in the revs, but more a case of the TT making more power at every point through the revs, and is probably much to do with the cylinder head, carburetor, airbox, and exhaust differences.

That's what happens when a Japanese bike has to meet USA EPA regulations.

EPA = power loss.

 

I second the comment about the TT350 being much better than the XT350 for dirt bike usage.

No comparison, really, as the TT felt like a true dirt bike with good suspension and good ergonomics, while the XT has pillowy-soft fork springs with tiny 36mm fork tubes (ridiculously small), and a goofy shape to the seat/fuel tank junction that felt a mile wide compared to the TT350.

However, compared to some of the tanks you can buy for dual-purpose bikes these days, the XT was not too bad.

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  • 4 weeks later...

If I recall, the cylinder heads are different between USA XT350s and TT350s, even though the engines look identical from the outside.

I think the intake valves and intake ports are smaller on the XT.

 

I have owned a 2000 XT-350M and a buddy of mine owned a 1987 TT350T back in the day, and I recall no situation of the actual powerband being moved up in the revs, but more a case of the TT making more power at every point through the revs, and is probably much to do with the cylinder head, carburetor, airbox, and exhaust differences.

That's what happens when a Japanese bike has to meet USA EPA regulations.

EPA = power loss.

 

I second the comment about the TT350 being much better than the XT350 for dirt bike usage.

No comparison, really, as the TT felt like a true dirt bike with good suspension and good ergonomics, while the XT has pillowy-soft fork springs with tiny 36mm fork tubes (ridiculously small), and a goofy shape to the seat/fuel tank junction that felt a mile wide compared to the TT350.

However, compared to some of the tanks you can buy for dual-purpose bikes these days, the XT was not too bad.

 

Thats interesting your right about the heads being diffrent they have a diffrent part number, but all of the guts are the same between the heads and there interchangable between bikes. Must be diffrent in the intake and exaust ports. This suggests that porting the xt350 head would lead to good results with rejeting.

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Thats interesting your right about the heads being diffrent they have a diffrent part number, but all of the guts are the same between the heads and there interchangable between bikes. Must be diffrent in the intake and exaust ports. This suggests that porting the xt350 head would lead to good results with rejeting.

 

Generally speaking , porting any internal combustion motor will lead to better performance . 😉

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  • 2 years later...

i know this is a old thread but i am wanting to know will the top end off a tt350 fit a xt350 as im in search of a head as my bike jumped timing and bent valves and guides and more the mechanic said i know the valves on the intake are larger by 1mm on the TT but by the way it looks when look at it they are identical same gaskets ecetra so if anyone knows if the tt350 head will fit as in take it all off complete and just bolt on to a xt350 let me know thanks

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