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

Don't go away, I'm not done yet!

Turning to the torque curve, it becomes clear why the bike pulls so well. A lovely steep and smooth increase from low down, fairly broad peak, coming in 600rpm sooner than the 250.

 

What I take from all this is that there is much room for further improvements. While I was initially disappointed that it isn't just a quick "bolt on this barrel and all your troubles are over" type of thing, realistically that was never going to happen with such a radical alteration to the bike's dynamics. Next move is to bolt on some different exhaust options. If the afr ratios change significantly, that would suggest to me that air is flowing better, then a bigger snorkle in the airbox, and finally possibly some porting and head work. I think larger valves and major head mods are beyond what I really want to do, and likewise I don't want to get into bigger carbs. I've only put 350 miles on the bike so far (so you might suggest maybe she's not yet run-in?) but there's a #2 being built this week, and as the miles rack up, I expect there will be some kits coming available as confidence builds.

In short, I think this may be a good base for some massive improvements (it's already a massive improvement in real-world riding and my main disappointment is that the electrodyno doesn't reflect what my arsedyno can feel!)

For the record, this test was done with standard airbox containing Twinair foam filter, standard exhaust system. Carb jets are 46/142 and the needle is down 1 notch (leaner than std) Gearing 14/49 tooth. Over the 350 miles so far, I've calculated approximately 65mpg (imperial gallon 4.54 litres) and that has involved lots of blipping up and down through the rev range I can tell you!

All constructive comments welcome

The seat of the pants results can be good & bad, I used to modify & fiddle with my bikes back in my early 20's ( I raced scrambles as they were called back then ) was also a motor mechanic as well, the hours & money I spent with modifications were over the top but the bikes were not as good as what we have today.

I used to spend hours testing with the seat of the pants in both engine & bike setup & sometimes I would loose my way, pretty common to get confused after a while.
The seat of the pants result tells me my TTR is better with the Staintune muffler but I might be wrong, these days I just leave the WRR standard engine wise & adjust the dampening & fit bars & levers etc. The WRR feels quicker than the TTR & the lads I ride with say I am a lot quicker on the WRR, it can be hard to tell by the seat of the pants feel but in this case it's correct.

Do what ever you are happy with but the painful fact is with engine modifications you will be chasing your tail, as you modify one bit it will have a flow on effect & so on, you will get there in the end but with a few why are I doing this.

I'm lucky in the fact I have both a TTR & WRR so I can choose on the day if I want the slightly quicker bike, Yamaha spent a lot of money building the WRR engine & is bloody good, uses less fuel & provides more power & this is what you are up against & good luck for the project. You are a better man than me putting the hours into this, I just don't have the time to do such, perhaps when I quit work in a couple of years.

Cheers Terry

Thanks for the support and encouragement. It's been a long but interesting journey and it's not over yet!

Martyn, that warm glow from starting the engine for the first time and not have it spitting bits of piston all over the garage door is still with me

Comparisons with the WR R are always going to be there, although they're very different bikes (which is probably why you still own both Terry?) Peak torque from the 350 is already higher than the WR though, and comes in MUCH lower down the rev range making it a very flexible engine that doesn't need revving. If I can eventually hit the 30hp that the WR puts out, with a more tractable and torquey low-mid range, that will be the engine Yamaha SHOULD have put in the WR R (watercooled of course) to make it an excellent dual sport instead of an enduro bike with an extra gear.

I'd love to see the results of a TM33 pumper conversion, although the smaller intake on the TK promotes torque I believe, and that is really what makes the bike rideable even though the horsepower figure is what draws the attention.

Back to the workshop...

I too am an avid TTR250 owner/lover and I've been seeking TTR250 performance upgrades.

… I've been watching this thread with some excitement for about four months now. I live in the USA and I use my TTR as my main enduro/trail bike - woods only use, not tagged to be street legal. ( Dirt use is my focus! ) I use to race hare scrambles and enduro. When I raced Hare Scrambles, my bike then was a very solid reliable Yamaha TT350. When I ran Enduro, moved up to a 1996 KTM 620EX/C. 

Wow… the TTR250 - the perfect combination for me today - now I’m 58 and I simply ride trails. ( At a very elevated, fast pace, I should add ) Being motivated to ride fast, my 2003 TTR250 has been the subject of quite a bit of performance enhancing thought and modification. 

I'm VERY EXCITED to see a 350cc upgrade kit coming .. I check this thread regularly for the most current updates and look for the opportunity to purchase a kit in the near future.  

Here is what I've done to improve my TTR250 ( and I look forward to adding another 100cc !! ) :

I’ve added a lightened flywheel. I had it shaved down and there was 1 lb 3 oz. removed. This simple move works amazingly well... this one modification alone helps transform the engine into something much more fun to ride. It’s now zippy, very responsive.

I recently added a 2003 WR250F muffler section. The stock WR250F muffler really uncorked my TTR250, adding much more power. Way more than the stock muffler, and more power than that YZR600 ?? titanium something something crotch rocket street muffler I had started out with. 

I’ve also added 2003 YZ250 USD forks & clamps. Again! Another super improvement over the stock 1980's style TTR250 conventional forks.

I've bumped up the seat hight using a old TTR125 seat foam directly on top of the low slung TTR250 seat foam, then stretched a gripper seat cover over the sandwich. WOW> This trick makes the bike feel taller and easier to ride in the woods! I can really corner like a bandit now that I can slide up close to the filler cap and actually stay there. It's also very easy to stand up on now. This is a cheap and effective modification that I highly recommend to others. 

I've cut out almost the entire top of the air box for better breathing, and I’ve added a "twin air" air filter. 

I’ve been working slowly with changes so as to get them all dialed in correctly for the best performance. In the ready room, are  sitting a pair of custom ground cams that I had made this summer, and also a 74mm WISCSO piston set. Right now, I'm waiting to see what the 350cc kit turns out to be like before I work on adding only 1mm to the bikes cc size. I also have a brand new 34mm OSO flat slide carburetor for use later on. The stock carburetor works very well, but I’m prepared to use something better maybe bigger if I need to.

The performance cams however; I am VERY eager to install. As far as I can tell, there is only one company advertising on the web ( Web Cams in the USA ) that offers performance cams for the TTR250 engine. They offer two different grinds; one is a mid to top end cam grind, the other is a low down torque cam grind. What I had ground for me was a grind that is very close to the Web Cams mid to top end cam profile - I used Web Cams advertised specs to go by while I was searching for a custom cam grinder who could make a set for me. The regrind Web Cams TTR250 cams run $550.00. I went looking for any and all performance reviews but could not find any. There has been only one set of each grind purchased from them. I know this because I asked Web Cams how many they have sold! So, I'll take it that this one subject is uncharted ground. I have also learned that Kibblewhite offers high lift springs and retainer sets for a .410 lift cam for the TTR250 engine. Interesting… no special cams yet there are performance valve springs and retainers available? I haven’t found anyone yet who has installed / have used high performance cams in a TTR250 engine. 

I feel that adding a nice performance cam set to a TTR250 with a 350cc upgrade should eventually make a huge difference in overall HP & torque numbers.

( Btw; I asked my grinder what the stock cam values were, and was told both cams are 300 lift. )

In case you’re interested, here's my new cam regrind details:

intake duration: 278 

Intake Duration at .050: 230 

Intake Lift: 320 

Intake valve clearance: 004 - 006

 

Exhaust duration: 278 

Exhaust duration at .050:  230

Exhaust lift: 320

Exhaust clearance: 006 - 008

Well… thanks for tolerating my comments. I just couldn’t read any more without shouting out with excitement; I’m pretty stoked to see a TTR250 350cc kit in the works! - TTR Keith

PS: Attached are a few pictures of my ever evolving, well loved, project TTR250! ( And the modified WR250F muffler )

 

Thank you, Martin!

I surely don't want to steal any thunder that the 350cc upgrade kit  is making ... but for sure, I'm eager to learn about / willing to try it / definitely into this subject!

 

Thank you for the compliments! I love the gold rims also. I'm a fan of the old ISDE look. I've even created a full gas tank sticker that reflects this theme and the first application of it didn't go so well. ( it lasted exactly one week )

I do have a few new ideas on how to get them to stick permanently, though. 

A special thread about the custom ground cam set is a great idea. I will do it as soon as I have some news to report, but you can always send me an Email if you have any questions before I get to making a post. (  bre66@windstream.net  )

I check this Email address a few times a week for important and private messages. ( or you can send me a head's up that you've sent a message here at this page? ) 

I did take the time to disassemble the wheels and have the rims powder coated in a "Ferrari gold" color. I also painted the hubs a "Yamaha" blue. I wish now that I had power coated those at the same time though, as the paint doesn't like to stick to the hubs. Oh well... MORE WORK AHEAD! 

About the head, and porting it: nope, not yet. I want to get the cams in first. Then find out what the jetting might be... then go forward from there. But I have a very knowledgable moto-X mechanic friend who knows quite a large amount about how to do it right. I'll be getting with him on that soon, also.

I'm wondering right now if anyone on this list may have an extra set of white raid 250 or white TTR250 side panels and a rear fender? I'd love to score some. 

Here is what my custom made fictional Yamaha ISDE fuel tank decals look like. Sitting next to my TTR250 is my old trusty friend of 20 + years now. ( the monster bike my friends are afraid of to ride ) A 1996 ISDE KTM 620 EX/C. Lordy! What a great bike that is! When Dick Burlson saw this a few years ago while at a local riding park, he got pretty excited and proclaimed that he wished he never sold the one he had! It's the dirt bike standard that I measure all of my dirt rides by. I'm working hard to get my TTR250 up to that bikes feel and pull and I think I'm getting close, as far as I can tell. The TTR's beginning to handle like the KTM, and I am hopeful that soon it will have arm wrenching power that I can use to abuse the chain with! Seriously though, I'm not ashamed to admit it, I love both bikes equally the same. Hahahah!  

You can see the old Yamaha titanium muffler and original fork set in the photo. I wrapped the street bike muffler with a blue anodized aluminum foil sticker material and added FMF Ti 4.1 stickers to it to help fool any onlookers! 

To get those large YAMAHA stickers to stay mated to the tank, I'm going to make a plate cover wrap from thin aluminum sheeting. The fumes from the gas seeps through the plastic, and work to push decal stickers away via large gas bubbles between the plastic and the vinyl.

BRING ON THE BIG BORE 350cc!

 

 

mossproof wrote:

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Thanks for the support and encouragement. It's been a long but interesting journey and it's not over yet!

Martyn, that warm glow from starting the engine for the first time and not have it spitting bits of piston all over the garage door is still with me

Comparisons with the WR R are always going to be there, although they're very different bikes (which is probably why you still own both Terry?) Peak torque from the 350 is already higher than the WR though, and comes in MUCH lower down the rev range making it a very flexible engine that doesn't need revving. If I can eventually hit the 30hp that the WR puts out, with a more tractable and torquey low-mid range, that will be the engine Yamaha SHOULD have put in the WR R (watercooled of course) to make it an excellent dual sport instead of an enduro bike with an extra gear.

I'd love to see the results of a TM33 pumper conversion, although the smaller intake on the TK promotes torque I believe, and that is really what makes the bike rideable even though the horsepower figure is what draws the attention.

Back to the workshop...

Yes I keep the TTR because it is a good bike & different to the WRR, The WRR is very much like a 2T to ride, if only Yamaha had fitted EFI to the TTR & raised the HP

Terry

---

 

Being an impatient chap (and it taking a little while for Steve's local 350 build to materialise ),  I took the opportunity of doing a short visit on my way to an electro-plating course near Burton-on Trent to pop in to see Simon and blag a ride on his 350.

I am really glad I did. I don't know why but I didn't expect the motor to sound as sweet as it did - perhaps it's the quality of the kit or a testament to Simon's spannering skills - I am sure we will find out when Steve's 350 is up and running 

Anyways up, Simon trusted my lardy ass with the 350 and led me off through his farmyard and hundreds of suicidal free-range chickens (scary things that fly out across your path from nowhere ) to a large field (which I guess is his own personal playground) in which to test out the world's first TTR350. 

The field looked large until I started giving the 350 the beans when suddenly it seemed to shrink at an alarming rate!  The 350 truly has the torque that Simon mentioned and easily broke traction in the high gears from mid-throttle. Fantastic fun and perfect for trail riding where you need the power mid range.

Can't wait to (a) get Steve's 350 built and (b) get a kit of my own to build 

Brian

PS I trusted Trish to take some video but, sadly, it is mostly of the ground - and no bikes apart from a tiny section which I will try and retrieve when I can get her phone off her long enough to transfer the footage onto my PC 

TTR Keith wrote:

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I too am an avid TTR250 owner/lover and I've been seeking TTR250 performance upgrades.

snip

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 Your bike is very similar to mine... even the same forks...

have you weighted it ?.... mines at 115kgs with 5 liters of fuel..

Brian hears one for you next time try a plumbers Arctic Spray Pipe Freeze kit next time get them screwfix or on the bay put bearing into a Styrofoam cup in a china mug cut a bit of Styrofoam to fit in top of cup spray the stuff into the cup leave for 60 sec take out and it should just drop into case that is at room temp or just put a blow torch passed over the case a time or two if its a cold day works for me. make sure you handle the cold spray and stuff with gloves or you be on your way to Hospital and they be trimming your fingers down a bit


Pug

I see Steve is using 4GY cases with a breather in the case. Could be handy to increase crankcase breathing.
Going to use a later type clutch?

That's a good idea there Pug. Saves an overnight in the freezer!

Looking forward to #2 hitting the trails soon

Steve is hoping to update the thread later but, meanwhile, here are a couple of photos of the man himself to show why I enjoy working with him 

Superb.

Great news - now the fun starts.

Congratulations Steve and well done. I can appreciate your glee and happiness.

Even Brian will feel chuffed.

Martyn

Great news.....time for some tuning now :)

Just spent an hour reading through this fantastic project.

Excellent work. Amazing persistence.

I'll get mine running first.

I got mine given to me as a non-runner. A mate and I have a couple of desert rides planned for 2019 - he's about a third of the way through putting a KLR650 sidecar together. I have been saying that the TTR is plan A. If it doesn't work as I expect, I'd go and buy something else. A practical 350 kit would qualify for something else.

Still, I've get mine running first.


Best of luck with this.

Hi Kimani!

Simon is in Morocco at the moment but he continues to sound very positive on his 350 build. I can understand why having ridden the bike myself a few months ago 

The last I heard from Steve was that he was also very impressed with his 350 build but is a very busy man so was struggling to put miles on the  engine.

However, the kit went together so well that we have had the confidence to order some more barrels from the foundry. I can't wait to get my own kit. I got a TTR250 ready for a power transplant......

Brian

Thank you Kimani - good to hear you are still keeping an eye on us 

Not much to report by way of an update other than I spent some time with Steve yesterday and did some fine tuning on his 350's carb such that it is running even better now.

His kids are back at school from today and, hopefully, when he has caught up on his backlog of work, he will be able to finish running his 350 in 

Brian

 

bad news with the frame love strata florida

I should be out on my 350 in the morning ))

the first batch are on order, 2as out on my 350 for a quick spin, flippin awesome. loving it

When I get the piston price confirmation we'll sort out a kit price and availability times. Hang in there!

Steve, is that headlight and bracket all custom?

-- Edited by bwaldo on Wednesday 16th of January 2019 11:58:09 PM

I want one of the screens for it, anyone got one?????

I too am waiting patiently. Just hope the shipping isn't too bad. Also, waiting to here what needs to be done carb wise...

Getting back on-topic

Just finalizing prices of head gaskets and we'll be ready for retail!

Brian and Steve are playing with carb settings on Steve's bike (#2), trying to get the mixture close with minimal changes (ie needle movement only). #1 bike is running Twinair filter, unmodified airbox, standard header and Motad end can (which is slightly more free flowing than a standard pipe) and I am happy with 48 pilot jet, 140 main, needle in the standard position.
I did run it with an FMF Q4 with no baffle, and the airbox lid off for minimal restriction, and a 48 or 50 pilot and 147 main seemed ok on the afr meter.
The upshot of this is carb mods will depend a bit on what pipes you're running, but some jetting changes are likely.