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

mossproof · Super Guru

350cc Big Bore Kit for the TTR250 - updates and gossip!

mossproof · Super Guru

New batch now back from the machine shop. Will get them ready for dispatch ASAP. Standby everyone. Yeeha!

Gadget964 · Veteran Member

Great news. How many did you end up with?

ttr steve · Super Guru

6 and if I have got this right, Brian is owed one and I have taken a deposit on one, so four will be up for sale

mossproof · Super Guru

It's 6 plus Brians - 7 total.

Gadget964 · Veteran Member

Please put my name on one of them. I have an engine split and ready to go. Just let me know about payment methods....
Cheers,
Mark

mossproof · Super Guru

Steve is dealing with sales through www.totallyttrs.com Contact him direct by sales@totallyttrs.com

Forgorin · Senior Member

Dibs, just sent you an email Steve. Once you send me the payment info, I'll send you the monies!

Michael

Dlight10 · Newbie

Ok my timeline.....

2004 had ttr

2008 sold ttr and went on the horse power hunt

Few bikes in between form TE610,KX500,FE650(still)

Found all the horse power I will ever need and then some in the Australian bush with injuries to prove it........

2019 got old and just wanted a simple e start 6spd air cooled armchair that was very forgiving with a little more grunt than the TTR250 I once had

Mid 2019 started thinking TTR250 but it was still down on the power so started looking for mods.

Then previously read about the 325cc kit on another forum, wasn’t convinced about reliability

Later 2019 found this post amongst others (petenz but more on this later.......) and hunted down a mint 2011 TTR250 snapped it up.(20hr round trip)

So basically from this very post and from the efforts I have seen from you fellas you have sparked an interest from me in this faithful old steed I once took for granted many moons ago.

I am quite picky when it comes to my mechanicals and it seems that you guys have covered your bases and have put together a quality product. The only issue I could find is the surface finish you speak of from sand casting and for me that is purely aesthetic which has no bearing on reliability. (certainly beats other alternatives that I have read about)

With further success stories hopefully to come I definitely will be in the market for one of these kits as I believe it will tick all my boxes for what I need in a bike that has a good balance between power, simplicity and reliability.

Some quick questions if I may?

Your thoughts on your 350cc kit coupled with the Rekluse Radius X that petenz has installed in his TTR250?

How is the efficiency on the cooling cycles with the fins on your barrels compared to stock with the extra power?

petenz would the Rekluse Radius X hold up to this kit In the format you have in your TTR250 with the lockup and engagement ability with those heavy duty springs?

Cheers and thanks in advance, love your work!

-- Edited by Dlight10 on Sunday 26th of January 2020 11:43:12 AM

ttr steve · Super Guru

Hi Dan

Interesting about this part of your post

I am quite picky when it comes to my mechanicals and it seems that you guys have covered your bases and have put together a quality product. The only issue I could find is the surface finish you speak of from sand casting and for me that is purely aesthetic which has no bearing on reliability. (certainly beats other alternatives that I have read about)

You talk about the finishes, and on the first couple of batches, they could have been a little better, but once fitted to the engine/ bike it was not at all noticeable at all.

Now the new ones are a different thing altogether, the finishes are pretty amazing, yes there are very small casting marks and bits, but fantastic looking things that anyone would be really pleased to fit to their bike, especially as they will be getting 100 more cc and torque that is off the radar!

Hopefully I will get some new updated photos soon smile

Hope that helps.

Steve

Dlight10 · Newbie

Hey Steve,

hope I did not offend anyone, I was only quoting mossproof...

” Please note that the limitations of sand casting, as opposed to the Yamaha die casting, mean the fins are slightly fatter than oem, and the surface texture is not as smooth.”

....and to that comment I reiterated that this would not be an issue for me even though I am picky across these kind of things normally. The outcome is a far greater gain than the surface texture issue stated.

But thanks for your post, great news on the new finish and thanks for letting me know that, like I needed my arm twisted hehehe.

look forward to hearing the success stories

Cheers.

ttr steve · Super Guru

No not at all, didn't think of it like that. All perfectly factual smile

Gadget964 · Veteran Member

Hi Steve,
I just wanted check that my email came through with the details that you required.
Cheers,
Mark

ttr steve · Super Guru

Yep got them, cheers Mark, will try and get a shipping quote later today smile

Steve

TTRfan · Super Guru

Picked up my 350 kit from Steve today. Very pleased with it! Not seen a red piston before though biggrin

If anyone else is interested in buying a kit then don't wait until Steve's stock is sold as it takes a long time to get a new batch made up as anyone watching this thread will know.... See here

Brian

My 350 kit 1.jpg

mossproof · Super Guru

I keep forgetting to point out:

The barrels are spray greased to avoid corrosion, and I haven't cleaned them thoroughly because of this and because dirt-in-transit will contaminate them as well. Please make sure they are thoroughly clean (hot soapy water or something like brake cleaner) to get rid of any residue from the machining and all the oil/grease. Smear the bore with clean engine oil afterwards to prevent corrosion. VERY important the bore is washed clean of honing debris.

Please check there is clearance for the starter motor by doing a dry-run build. I have reduced the fins at the back as they were a bit long - should be enough, but if I haven't taken enough off it's easier to do before the final build.

Make sure whoever machines the cases bores into the case deep enough for clearance of the barrel - there is a bulge that needs skimming lower down. (See the pic a few pages back in the thread)

If I think of anything else I'll add it here, and maybe Steve could put a note in each kit?

Looking good Brian. Is the rest of the bike ready to receive?

TTRfan · Super Guru

Good points Simon and thanks for the heads up!

I am going to replace the 325 (Thumper Racing kit fitted) engine in my current trail TTR with the 350 engine once built so, yes, I have a bike ready to accept it biggrin

I have a few jobs to finish off in the workshop first but then I can drag out the bottom end I have stashed away waiting for this moment and send the cases off for boring. I might use Barum Engineering in Barnstaple who did a good job on Steve's cases.

Brian

ttr steve · Super Guru

mossproof wrote:
I keep forgetting to point out:

The barrels are spray greased to avoid corrosion, and I haven't cleaned them thoroughly because of this and because dirt-in-transit will contaminate them as well. Please make sure they are thoroughly clean (hot soapy water or something like brake cleaner) to get rid of any residue from the machining and all the oil/grease. Smear the bore with clean engine oil afterwards to prevent corrosion. VERY important the bore is washed clean of honing debris.

Please check there is clearance for the starter motor by doing a dry-run build. I have reduced the fins at the back as they were a bit long - should be enough, but if I haven't taken enough off it's easier to do before the final build.

Make sure whoever machines the cases bores into the case deep enough for clearance of the barrel - there is a bulge that needs skimming lower down. (See the pic a few pages back in the thread)

If I think of anything else I'll add it here, and maybe Steve could put a note in each kit?

Looking good Brian. Is the rest of the bike ready to receive?

Good Idea
Michael you read this post? Your order will be on it's way soon I messed up the label and will get it sorted tomorrow
Steve

Forgorin · Senior Member

Awesome. Looks like it will be a spring build.

I just hope that I can do it. I am not very good at these things...

mossproof · Super Guru

If you have a manual and/or Brians how-to guides, take your time and be clean and meticulous, fitting is straightforward.
Jetting the carb might be a fiddle, as Dan is finding out with #3, but we're here to help!

Kaos · Senior Member

When you are splitting the engine cases to get them bored out for the bigger barrel, what are you guys doing with the cases?. Do the cases need to be stripped right out of bearings etc, or just covered up somehow to protect from swarf from the milling process etc???

Gadget964 · Veteran Member

Mine's going to be completely stripped, modifications made, cleaned, then rebuilt- Most of the engine will be fresh.

TTRfan · Super Guru

Kaos wrote:
When you are splitting the engine cases to get them bored out for the bigger barrel, what are you guys doing with the cases?. Do the cases need to be stripped right out of bearings etc, or just covered up somehow to protect from swarf from the milling process etc???

Hi Steve - are you thinking of going big bore? biggrin biggrin

I think it depends on how well you know the history of the engine, its mileage and how well (or not) its been treated in its lifetime, as to how far you go.

It is relatively easy to get the old bearings out undamaged by heating the cases. I found that most of them just dropped out after heating them in the oven. They can then be re-used if OK.

I would however suggest to at least replace the main bearings as they aren't stupidly expensive - see here

I recall that Simon Chance masked off his bearings and then left the cases in the parts cleaner with the pump running for a long time to be sure of getting any swarf out.

Brian

dlee22 · Senior Member

I covered mine but with mixed results. In the end I replaced them all using Brian's oven method, easy enough!

Forgorin · Senior Member

Well, it arrived. The work starts this weekend...

TTRfan · Super Guru

Excellent news Michael!

How far have you got with your preparations - are you re-using your existing engine?

Maybe you could start your own thread and add some photos as everyone's experience will be slightly different, especially as you are in Japan wink

ttr steve · Super Guru

Forgorin wrote:
Well, it arrived. The work starts this weekend...

Good news and get on with it!

Steve

Kaos · Senior Member

ttr steve wrote:
Forgorin wrote:
Well, it arrived. The work starts this weekend...
Good news and get on with it!
Steve

Steve

can you check your messages request sent a while ago

Steve

Gadget964 · Veteran Member

I ordered mine a little while ago, but had to get Steve to hold off on the delivery until I knew that I'd be at my new delivery address.... Now that is all sorted, there should be one coming to Australia very soon.

ttr steve · Super Guru

Hi Mark

Will be booked with the courier first thing Monday morning, I got your email

Cheers

Steve

Gadget964 · Veteran Member

Thanks Steve, I'm just excited that I'm getting my hands on one...

Exporting to Japan & Australia; where else are they going?

Rossyboys · Veteran Member

Just so happens I bought a Yamaha TT-350 last week for $200 AU, from a mate that bought it from another mate that rode around a good part of Australia. 30,000Km on the speedo now. Hadn't be started for a while and the carbi was very dirty and needs a service kit. As the Wiring needs a tidy up and it will be a good bike on the mates farm out Cobar for my son, A step up from a DT-175

Forgorin · Senior Member

Good thing there's no wife to complain. Had to take the front end off to get it to fit in the elevator...

Now to figure out how to get the engine out of there...

Gadget964 · Veteran Member

Ok... This weekend the first TTR350 build in Australia is about to get under way.

I've had the cases split on my 96 TTR for several months- but I really wanted a kick start back-up. I ended up finding a reasonably low km 2005 which will be the donor. A few weeks ago I had the new blue on the dyno as a baseline; I didn't care about AFR etc for this one, I was just looking for peak HP. I can't recall what torque they said that the stock motor put out, but it was just on 20.6hp.

I'll be getting my suspension tuner/mechanic to do the work for me as he is an absolute perfectionist. I'm predicting that the motor will basically be new when I get my hands on it (he once worked on my 20,000km DRZ400... It had one original gear left in it when I got it back, everything else was new. His comment at the time was "There's no point putting a 30000km top end on a bottom end that will last 10000km) He'll also be flowing the head a little for me.

mossproof · Super Guru

@ Rossyboys: If only Yamaha had put an electric leg on that motor it would have saved me a lot of heartache!

@ Forgorin: I admire your tenacity in getting virtually the whole bike to your apartment in the lift, although I'm watching your progress through my fingers just a little

It's not your usual workshop environment! (What happened to the rear subframe by the way?)

@ Gadget964: Glad you've started with a dyno run. I'll be interested to hear the results with the gasflowing. Any idea what pipes you'll use yet?

Kaos · Senior Member

Gadget well done getting the baseline dyno done. Mine did 23hp with a 2mm overbore headwork shorty header. I suspect the 350 will show great gains in torque so should be a great ride.

Gadget964 · Veteran Member

Mossproof- I'm planning on a Lectron carb and custom, slightly oversized, shorty stainless header... most likely matched to a DominatoR muffler, but I'll see what's available at the time.

JOHNYBOY · Super Guru

jeez them lectron carburettors are well expensive just looked on flebay

TTRfan · Super Guru

It would be fun if someone tried fuel injecting a TTR350 wink

Gadget964 · Veteran Member

At least tuning should be easier--last TTR that I tweaked was very sensitive to altitude changes.

mossproof · Super Guru

TTRfan wrote:
It would be fun if someone tried fuel injecting a TTR350

You and your bright ideas Brian

Maybe while you're self isolating in Devon you could gather the bits by internet and have a play. How hard could it be???

ttr steve · Super Guru

2nd that, c'mon Bri wink Do it!

tiddler · Veteran Member

Megasquirt or more likely Microsquirt would be a great starting point, plus a throttle body off any modern bike and you're away Brian!

TTRfan · Super Guru

It's a bit beyond my old "imperial" brain - I have only just begun to understand how surface carbs work disbelief

Anyone else fancy taking on the challenge????

Forgorin · Senior Member

Moss, it came that way from the previous owner. I think he cut it off...

mossproof · Super Guru

TTR350 number 4 rode out of the garage this morning with all 6 gears! It rode out yesterday with only 1 - misaligned selector, oops!
Now for some illicit lockdown running in. Back roads only ha, they'll never take me alive...

Gadget your's will be a ktm killer for sure.

TTRfan · Super Guru

Well done Simon!

I will get going on mine again once I have finished my gardening duties (Dig for England!) - or the rain returns.....

Brian

Gadget964 · Veteran Member

Well: I managed to get my motor to my mechanic for its rebuild just before the beer bug shut us down. So even if he manages to get it all milled and rebuilt, I can't get near the bloody thing (450km away) due to travel restrictions (I did hear talk of May 11 over here today)… so I've been working on getting the frame ready to receive its new heart.

TTR600 headstem fits in nicely. I just have to weld in a new steering stopper, which I fabricated today. Hopefully I'll be ready to prep and paint the frame within a week. And have it all sitting here waiting. I've decided against fitting the oil cooler just yet as the motor may end up in one of our other bikes for some reason. Once it's all dialled in I'll make a decision about the cooler.

mossproof · Super Guru

Frustrating!
I would definitely fit a cooler, whichever bike it goes into, considering the extra performance mods you're going for, and your climate. More oil capacity and cooler oil gotta help, but certainly not essential for initial setup.
Here's the cooler I've built for #4. Slightly bigger than ideal for the gap it fits in (damn that Acerbis is huge!) but it holds a lot of extra oil. (85ml)

Gadget964 · Veteran Member

One thing that I am considering with the oil cooler, is how much riding am I actually going to be doing on it. Due to injury (from 6 years ago), combined with supporting my sons Desert Racing, I've only been able to get in about 500-1000km per year. So regular oil changes will be easy.

I'm hoping that in the not too distant future I will be able to increase my ride time... If it turns out that I can get back to doing multi day & long trips, the oil cooler is likely to go on.

-- Edited by Gadget964 on Monday 13th of April 2020 11:24:48 AM