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Post Info TOPIC: 350cc Big Bore Kit for the TTR250 - updates and gossip!


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350cc Big Bore Kit for the TTR250 - updates and gossip!
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That's great Gadget. Looks schmick.

Should go schmick too.

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'73 RD250, '76 RD400, '80 XS1100, '81 RD373LC, '96 Tiger 900/sidecar, '02 TTR250



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20200523_101000.jpg

 

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I gave the 350 a bit of a local run this morning to get everything settled in. The motor is exceptionally quiet with no weird noises at all. With standard 250 carb settings, it runs surprisingly well--but it definitely needs adjusting. Rich in the bottom, feels OK up to 80kph, then feels a bit restricted after that.... I didn't play with adjusting any of that in this run as I just wanted to get some time on the motor. Plus I should find out next week when my Mikuni arrives, so I'm not going to spend too much time on a carby that's coming off anyway.

As I did a complete bike build, I have also had to re-adjust the new chain, head stem bearing tension and handlebar position.. An interesting point about the TTR 600 forks- I have somehow ended up with 30mm more ground clearance than my sons TTR (which has DRZ400 forks)







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First mud!
Bike looks fantastic. Somehow looks leaner than the old tt, despite the use of the plastics. Maybe it's the height?
I think the ttr engine is quite tolerant of rich settings. Looking forward to hearing how the Mikuni goes.
Good work,
Simon.

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Looks meaner you mean!

Flipping good job Mark, why change the forks? did the ttr axle fit or you had to make a modification?



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Ended up with full TTR 600 front end- triples, forks, axle, spacers, wheel, brakes, speedo drive.

It'll end up with a better set up for the desert riding that I do, and more adjustable than the 250 forks if I change where/how I ride.



-- Edited by Gadget964 on Saturday 23rd of May 2020 07:03:25 PM

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VideoCapture_20200602-200619.jpgFour hours on the meter now. 121km today without hitting reserve. I spent the day with my son on his TTR.

They feel absolutely nothing alike. The 350 is very torquey, is a hoot to ride, and will leave the 250 behind on any run... Except, having been out of the game for so long, I'm heavy and unfit.

Still, you just want to play.



-- Edited by Gadget964 on Tuesday 2nd of June 2020 11:29:02 AM

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Sounds great, is it still got the original carby or the Mikuni? How did it run?
Where were you riding, up Mildura way looks like Mallee scrub.?

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Still original carby at the moment, waiting for the Mikuni to arrive. It just feels like it has more to give... But apart from some wide open deceleration issues, I'd say the carb is currently set pretty well.

And yes, Sunset Desert. Just a little play as a shakedown before doing anything too big.

Liam & I both broke mirrors on trees today as we were riding on some pretty tight, whooped out tracks; so shopping tomorrow for replacements. Also on tomorrows agenda, is checking to see if anything came loose. Nothing obvious so far, but will check.

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Good news, I am sure you will get bike fit soon smile



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I like the torque so much I didn't want to risk losing it by opening up the top end, which is somewhere I rarely go.
Glad to see you're running her in gently

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Another 286km yesterday. Running sweet, averaging about 15km/lt. I lost a header shield bolt.

The difference between the two TTRs is amazing. My son is now looking to trade his TTR 250 for an XR 400 or similar. 

Apparently my new carb is at home waiting for my return.

VideoCapture_20200605-135736.jpg

 

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-- Edited by Gadget964 on Saturday 6th of June 2020 01:02:57 AM



-- Edited by Gadget964 on Saturday 6th of June 2020 01:16:55 AM

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Great result glad its running well. I'm riding up there in August doing a Mildura - Murrayville return, two days.biggrin But Hattah is cancelled no
It will be interesting to hear how the new carb effects performance. Are you going to open up the airbox more, bearing in mind there's been a 40 percent increase in displacement?



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The airbox lid that's on it has two holes in it... With the way that the bike already runs, I doubt that it will need any more. I will also try it on an unmolested lid as well.

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Mikuni is in.

Only been run in the shed so far, but very snappy response.

1.jpg



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Was it an easy bolt in?


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Throttle pull is on right side, so needs a bit different angle to get it in. Not difficult, just different.

To allow for the right side pull, you also need to modify right-upper engine mount (I just replaced it with a spare left sided mount that I had) and an little position adjustment of the shock reservoir mount.

 

20200608_115841.jpg



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How much was the Mikuni please and why change over to that carb?

Just interested.



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I just had a whole heap of stuff typed, then my old man rang.. So I lost it all and have to start again.

I'd always planned on going to a bigger /better carb when I was setting up the 350. Theoretically the Mikuni will really "wake up" the TTR... With the 1/4 pull throttle and pumper it should give the bike a bit more snap off the bottom. My son mentioned that it feels like it has more to give after riding it last week.

www.mikunioz.com/shop/yamaha-ttr-250-mikuni-tm33-8012-pumper-carb-kit/


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Gutting when you lose something you have put thought and effort into Mark cry

There will be a lot of interest in your carb conversion and, cheeky ask I know, would you be willing to start a new thread in the Carb sub forum please?

You have put some great photos on the TTR250 FB Group and, if it helps, I would be willing to copy them over if you start the thread?

Cheers

Brian



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You can add to the carb threads if you like Brian. As general fitment, it can be used for all TTR250/350's. But from my perspective, anything that happens to the carb from the initial fitment, will be specific to my 350- so may not be relevant to 250's (or those at different altitude or humidity). It will be interesting to see how it goes on the road in the next few days. Once tuned, I'll be getting another dyno done.

Even with the standard carb on, the 350 kit has a significant- seat of the pants- gain over the 250. Every now and then I get asked if it's worth it... Hell yeah. Granted that there is a significant financial hit (especially with poor exchange rates and import duties- I could buy a low Km DRZ400 for what the motor cost to get done) But this bike is something really special, and in its current configuration its helping to draw attention to the Totally TTRs 350 big bore kit.

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Your son looks like he's more in control of the beast (see photo in AdvRider).
Bloody kids!

Interesting that the stock carb was only giving 15km/l. Wonder if that had much to do with your right wrist on your new old bike?


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150 km per tank is all we could get on any of our TTRs. Sand takes a bit of work.... And yeah, playing with the right hand.

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I managed to get the bike out for a short run yesterday. The Mikuni definitely gives more punch off the bottom. I never went to WOT, but mid-upper needs dialling in. I have the AFR meter in the shed now, so once I get a heap of spare parts tidied up, I'll be able to get connected.

For the brains trust: What do you recommend my target range be? And just confirm for me that low number =rich, high numbers =lean.

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Correct - low=rich, high=lean.
Anywhere below 11 is wasted fuel IMO. I felt that above 13 in the mid range felt flat although it is still on the rich side of stoic - the supposed "ideal". I feel most comfortable in the mid 12 range, which is a compromise between best rich torque and best power at WOT according to the SAFR website I linked a few pages back, with enough richness to help keep combustion temperatures reasonable.
Of course, the pumper confuses the issue by lobbing in more fuel unmetered when you twist the throttle, so you want to be measuring at steady rates I think. If you get 12 - 12.5 while clinging on with the throttle full open, and 12 - 13 at tickover, then start playing with needle position for the best "feel" in the mid ranges, and fuel screw for the best "zap".
Welcome to the merrygoround - change one thing, affect something else unexpected, start again...! Keep a note every time you change something - it all becomes a blur after a while!
Good luck, it'll be worth it.
Stay sane!
Simon.

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OK. First issue was not wiring correctly... Got that all sorted and the AFR calibrated, then with the bike running at idle had an afr of 22.4... Hmmm, that's the same base reading it has when exposed to air (I'm using exhaust tip meter - at the moment) I re-read the instructions= air leak in system. Apparently they were right, I found a really crap connection between the header and muffler. Pulled that apart and re-realed. I will start again tomorrow.

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Just found your Advrider thread Gadget. For those without the patience to search:

advrider.com/f/threads/project-ttr-350-because-i-can-because-i-want-to.1441829/

Think your lad will be dissappointed by an xr4, but he looks like he's got the skills to make it work!

Does your afr pickup sit at the end of the tailpipe or have a sniffer tube you insert? I'd be interested in the details.


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Well, number 6 is on the road. I've put 100 km on it is far. I have not 'opened' it up yet but, it sure does have much more grunt low down. Ive got a standard airbox and a free flow exhaust. i haven't done anything to the carb yet. Perhaps this weekend after I have a few 100km done. It does stumble a tiny bit if I blip the throttle. I assume I can fix that with the air screw.

Anyways, was a tough trial getting it built with some trouble shooting thrown in. I doubt I could have done it with out the existing threads here on the forum and help from various inmates. Thanks sooooo much guys. I can't wait to be able to put the bike through it's paces.

P.S. My raid has a new name Nessie. HEHE

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Little sh** has skills alright... It's a disappointing, but bloody good feeling when your children can out-ride you.

I've just been looking at the AFR again, I'm getting inaccurate readings from the sniffer tube at idle... So I've just mounted the plug on an old header. The recommendation on fitting for mine was 24" from exhaust port, which puts it at the start of the heat shield.



-- Edited by Gadget964 on Tuesday 16th of June 2020 02:06:29 AM



-- Edited by Gadget964 on Tuesday 16th of June 2020 02:07:03 AM

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I'm looking forward to how it works out. It's a shame you couldnt get a before and after dyno run.

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Not a bad thought. I had a dyno done in 250 form... I might see how receptive they are for letting me change carbs and doing a Teikei v's Mikuni run (it shouldn't take me too long to swap over.

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Well, it's been a week. Did you blow it up at Hamilton Gadget?



-- Edited by mossproof on Thursday 25th of June 2020 09:16:07 PM

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Didn't end up taking it- Sold my sons TTR, dropped that off in south west Victoria (they paid for delivery!)- then ended up in the middle of NSW to pick up his next bike (about 2000km loop all up). After riding my350, he wanted a few more cc, so ended up with an electric start XR400.

I'm pretty sure the 350 will get out in the next few days.  The bike has 11.5 hours on the meter now.  I'll get a few trail rides in to make sure that I'm happy with the way it's running, then re-check AFR...... Then Dyno again.  

 

I did manage to get my new tank fitted though:

 

20200621_164256.jpg



-- Edited by Gadget964 on Thursday 25th of June 2020 10:33:00 PM

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I'm still loving your bike. Be interesting to read the dyno result and comparison with the XR400.

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Hello
My TTR uses the Kawasaki ZX11 piston
Displacement is 270cc
Carburetor uses Mikuni TMR32
Very satisfied, but also very interested in the 350cc kit
But it looks like it's sold out
It's a very attractive kit
Do you plan to sell it again?

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Welcome to the forum M from Japan smile

We hope to be doing another run of 6, just checking with the foundry, they have sold very well and 13 x 350 kits are now out in the worldsmile



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oki


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Thank you for providing a great product
I am very happy to be resold
I definitely want to buy it

My TTR has the starter motor removed
We plan to combine the 350cc kit and FCR-MX(37mm)
I'm looking forward to seeing what kind of TTR it will be

Thank you

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Only a little run today, needle lowered one clip position. The mechanic that built the motor was reluctant to get off it. He said "I could ride this bloody thing all day"

So my son told me today that I'm racing the TTR next month at the Farmers 6 hour enduro... After tomorrows ride I guess I'll be pulling out the suspension to get it dialled to suit the bike.

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Awesome, let us know how you get on smile



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ttr steve wrote:

Welcome to the forum M from Japan smile

We hope to be doing another run of 6, just checking with the foundry, they have sold very well and 13 x 350 kits are now out in the worldsmile


 Any update on the 350 kit availability? Deposit required?

 



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New batch of castings being heat treated today. Run of 6 - small enough not to frighten my machinist (doesn't take much!) large enough to reach min order quantity for custom pistons. Going on past experience, expect a couple of months to pass before they're ready!
Steve at www.totallyttrs.com deals with sales: sales@totallyttrs.com


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oki wrote:

Hello
My TTR uses the Kawasaki ZX11 piston
Displacement is 270cc
Carburetor uses Mikuni TMR32
Very satisfied, but also very interested in the 350cc kit
But it looks like it's sold out
It's a very attractive kit
Do you plan to sell it again?


 Hi Oki,

Is this just a 3mm overbore, or are other mods required to fit the ZX11 piston?

How does this affect the compression ratio?



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One of my ttrs had a zx9r piston, trouble was it was warn and burning oil so never found out much about it myself but apparently the previous owner was competitive in the enduro class he raced in.
. Glad someone else found a similar modification.



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oki


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IanU wrote:


Hi Oki,

Is this just a 3mm overbore, or are other mods required to fit the ZX11 piston?

How does this affect the compression ratio?


Hello IanU.
Cutting the top of the piston.
There are also Japanese shops that sell cut pistons.
http://hpo-japan.com/service/ttrboaupkit/ttrboaupkit.html

The calculated compression is about 11.8:1.
RC-SUGO (YAMAHA racing parts) high lift camshaft is also used.
I think the actual compression is not so high due to the influence of the high lift camshaft.



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Hi Oki, 

Many thanks for the reply, interesting information.

Ian



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