A forum for owners of Yamaha TTR250 trail and enduro bikes!

mossproof wrote:

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JOHNYBOY wrote:

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why not vent it to atmospere up the frame & to the back like they did on a lot of british bikes

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Well the breather sucks as well as blows - every time the piston goes up and down, so you risk drawing dust/water into the crankcases, quite apart from the oily mess that will build up (not a problem with old British bikes, which were an oily mess from the factory

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Add a filter to the end.  You'll see it on most road race bikes.  They have a small in-line catch bottle with a filter down line of that.  Of course, that depends on how deep you want to go and where you're going to put it.  S'pose that's why the manufacturers stick the crankcase vent into the airbox.

 

 

Why am I looking at this thread?  Well, I have just picked up a dismantled engine... the brain is working.  Just reading.  Probably wont happen as I've got too many other irons in separate fires.  Surely enough to keep me going for a couple of years.  I'd best get into one...

 

 

 

 

-- Edited by tripodtiger on Saturday 30th of July 2022 02:28:04 AM

Oh, the bike also makes one hell of a banging noise on start up. It sounds like the pistion is hitting something something. Once the engine catches it goes away. Any ideas?

Well my 350 kit is finally underway. At last. Engine is out and cases off for machining.

ttr steve wrote:

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Good news Steve and remember we all like to see photos

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 Will do. All good so far, everything looks good internally when pulled down, got all the new bearings gaskets etc required.  And just heard the machining has been finished and looking good.!!!

Looking forward to seeing your results Steve, once running in and tuning is done.
Good luck!

So its list of mods:-

WP 48mm forks, Brembo front brakes & braided brake line. Magura fat bars and Magura levers. All off a CCM404e.
Wilbers rear shock.
WR250f footpegs
Totally TTRs 350 kit with ported head and 36mm Keihin PWK carb. Modified airbox.
Totally TTRs shorty header pipe and GYTR muffler.
Powder coated rims.
Custom higher seat.
B and B bash plate (not shown)

Anyone want to buy a WR250f (280!!) ?? :)

 As well as my TTR250 big bore 350 build, I have also just completed a full resto on a 1986 TT350, powder coated frame, full engine and suspension rebuild, with a full TTR front end.  The TT350 I use for Vintage Enduro pre 1988 class.  

Here's some pics. 

Both need running in. So far I have only managed to put half a tank of fuel through the TT350. Its very strong down low and through the mid range. And it feels bigger and wider to ride than the TTR. The TTR250 feels slimmer, shorter, turns faster and feels like it might make a bit more power, revs quicker, and better brakes. But they feel quite similar to ride. But the E start alone makes the TTR much nicer.  

 

Got out for two days riding bush tracks on the newly built TTR350. Running really well with loads more torque. Its a good hill climber too! Well and truly fast enough through the trees for me.
Pic of a log crossing on one track wrecked by storm damage, you get so far in you don't want to turn around. It wasn't all like this!! So many trees down it was hard to find a path through. Otherwise brilliant couple of days riding.

I've recently sold A dr250 to make the 350 susuki fitted a different crank increasing the stroke  . So it's a big job to do the 250 .but the 350 could be bored .

Still have the ttr though 

Kaos wrote:

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Got out for two days riding bush tracks on the newly built TTR350. Running really well with loads more torque. Its a good hill climber too! Well and truly fast enough through the trees for me.
Pic of a log crossing on one track wrecked by storm damage, you get so far in you don't want to turn around. It wasn't all like this!! So many trees down it was hard to find a path through. Otherwise brilliant couple of days riding.

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 Love that picture 

Good move!!

mossproof wrote:

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Some nice gentle running-in there Steve!
It's all in the torque. Max power at max revs is irrelevant in the woods

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 I'm going to call it run in. 3 days of bush riding but only about 200 km but a lot of hours. Time for an oil and filter change.  I must/will put an hour meter on it!  Very happy with it.

 

Mate on his kx450 pulled up sore from the ride, but with the TTRs plush suspension, smooth power and a soft seat I pulled up fine.  I thought gee this TTR is quick now, then I rode the KX450. That was stupid fast.  Repeat, stupid fast.  Fun in open terrain but the TTR is fast enough for my old bones, 60 next year,  and very fast through the bush.

Yes enjoying the added torque. Monos!! I'm also running taller gearing now, previously always a 13T now a 14T front sprocket,  and finding it pulls it nicely.  Even with the taller gearing with the 350's torque I was using second at slow speeds mostly whereas previously it would have been mostly 1st.  And it's cured the 250s weakness, when the speeds are up and you come up fast on a puddle/log/hole etc just twist the throttle and lift the front over. The 250 struggled there.

Very capable bike, so thanks for engineering the 350 kit!!!  

I am also contemplating removing the WP USD front end and putting the bike into "stealth mode" with conventional forks and fork boots!!  I like the idea of a sleeper, fairly stock appearance but with trick suspension and motor. Even though I like the current WP front end set up and it works really well.  I can't use the original TTR forks, they are doing duty in my vinduro bike, the 1986 TT350.   Gadget has sold me a full DRZ400e conventional front end. Front wheel, brakes, forks, triples.   I've had these forks previously, 49mm Showa cartridge forks with modern internals, fully adjustable. I'm confident I can get them as good as the current set up.  If not I can always bolt the WP's back on. 

Oh I still have a bigger 38mm PWK carb to try yet!  I'll see which one feels best to ride then some dyno time with both carbs 36/38 later in the year.

Getting close with jetting.

 

-- Edited by Kaos on Monday 8th of May 2023 01:26:31 AM