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Discussion Starter #1 (Edited)
Well been plugging away on this for 7 months or so, but I finally buckled down and wrapped it up. I have some tuning to do I imagine and need to chill for a while till its got a few miles on it, but she runs like a top. Im hoping the gearing is a good choice, but I suppose I will get that worked out as well. it is 15-50 now and seems great so far in the first 5 miles I drove it this morning. So here goes. By the way I cant tell how much lower it is for sure yet (read below), but 6th is a fair bit taller gear.

this is a video and should be clickable.

Untitled by dolphaxel, on Flickr
https://flic.kr/p/vvcdJs

I meant to get some base numbers but forgot. So if anyone has a stock bike as far as motor and gearing with a tach I would like a few numbers to compare. Something like this
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What im after is how close am I to the stock 1st and how much drop do I have on the top end. Thanks
 

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Can't you just look at the factory specs for gear ratios in each gear, factor in sprockets and tire diameters of course, to get your answer empirically? Simple math.
 

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Discussion Starter #4
Congratulations Vanilla!

Refresh my memory please, what are the mods that you made to your engine?

Brian
Brian, its a 2001 ttr225 motor. So it should have the wider 6 speed. in addition to the gained bore and stroke I did the high compression piston. It also has an oil cooler bolted on. I think thats it for the big stuff, but I did do a new con rod, big end bearing, valves, springs, seals, hardware, ect. should be a solid ugly duckling.

Can't you just look at the factory specs for gear ratios in each gear, factor in sprockets and tire diameters of course, to get your answer empirically? Simple math.
thanks fred, Ive done the math thing and think I know whats what, but I wanted a little back up to be sure I did all the math right.
 

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Brian, its a 2001 ttr225 motor. So it should have the wider 6 speed. in addition to the gained bore and stroke I did the high compression piston. It also has an oil cooler bolted on. I think thats it for the big stuff, but I did do a new con rod, big end bearing, valves, springs, seals, hardware, ect. should be a solid ugly duckling.
Cool!

I am still a few weekends from (hopefully) firing up my TW226 6-speed project. I'll be interested to hear how yours performs.

Are you using a TW or TTR carb?
 

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Discussion Starter #6
Im just using the tw carb. I have the old style carb which I think I remember hearing someplace that was the easier one to tune, but I could be imagining things. when I ran it this morningit actually seemed to have better pick up than my 200 which seems odd because it was tuned to the 200, but what ever. I gotta say first impression is that its gonna be awesome!
 

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I totally love the upgrade you, TWBrian, and others have done to the lowly TW. Has anyone done a 250cc upgrade?
 

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I am thinking that you may not need to add any more fuel than an already richened up 200 uses...Also I doubt that the early carb is easier to tune than the later cv carb. Perhaps the main reason Yamaha went to the cv carb is because it is much more tolerant of lean settings....you can not just yank the cv carb wide open right off idle like you can with the early carb. Well you can, but the slide will open at its own pace...slowly to avoid stalling. For this reason I think the cv carb is probably easier to tune as abrupt throttle openings are buffered. I do think the early carb makes more power down low and pulls harder right off idle. I much prefer the early carb for off road, but I have no issues with the cv carb for the most part, but given a choice I do prefer the early carb...
 

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Discussion Starter #11
couple more runs down and I still have work to do. It seems to run a little hotter that my 200 did, so I need to keep tuning. I wonder how much the higher compression will raise the temps though. It seems that when I pull a hill the temp come up faster than they did before when Im in the throttle a good bit. I did step up from the 110 main to a 112.5 main and it seems to pull a little better now. Im going to do a couple plug checks proabably later this week or next to see how close I am. also I did use the gear calculator and it looks like 1st is almost a dead line up and in 6th at 55mph I have about 1K RPM drop for reference. most important the 4-5 drop is gone. seems I have been using 5th around 30MPH and grab that last gear above that driving around town.
 

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Have you tried higher octane gas in it yet? It might help it run cooler VG.
 

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It seems to run a little hotter that my 200 did............................
Nice job! I have plans to increase the displacement on my TW though I am happy with the 5 speed.

However, unless you are using a thermometer I think it is more placebo than actual temperature increase that you are experiencing. New paint and oily finger prints can smell hot when first starting an engine. And maybe there is a little more friction with new rings in a freshly bored / honed cylinder, but that should go away in a short time. Go by what the spark plug says. If it is the right color you are done. Put a some miles on it. I bet everything is just fine.
 

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I second the higher octane fuel with the higher compression. It should run cooler with higher octane fuel. Any thought on heat range of the plus to adjust for the compression change as well?
 

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Discussion Starter #15
it has premium in it now. Not planing to run higher octane than that, but I don't think I should have to 10.25-1 isn't that high of compression really. I understand about paint smells and such, but im closely watching the cylinder head temp read from the plug via the trail tech. it hasn't peaked abouve 375 yet, but the stocker rarely got that high unless I was running it really hard off road at low speed. Ill keep an eye on it and keep it under 400. I would like to run it around for 100 miles or so before I run it hard enough to do some plug testes.
 

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Great! You are using a thermometer. I bet once your rings seat things will cool down. How are you breaking it in?

I am just curious -- what is your piston to cylinder wall clearance? Wiseco says .002" minimum but I like to go bigger, about .0025 to .003. The same with the ring gaps. A thousandths or two thousandths bigger isn't going to hurt anything and the extra clearance comes in handy with the piston and rings if thing really start to over heat.
 

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Great! You are using a thermometer. I bet once your rings seat things will cool down. How are you breaking it in?

I am just curious -- what is your piston to cylinder wall clearance? Wiseco says .002" minimum but I like to go bigger, about .0025 to .003. The same with the ring gaps. A thousandths or two thousandths bigger isn't going to hurt anything and the extra clearance comes in handy with the piston and rings if thing really start to over heat.

Excuse my nooby question, but could a too-big gap there lead to more oil burning?
 

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Excuse my nooby question, but could a too-big gap there lead to more oil burning?
I am referring to the first and second compression rings. The rails on the oil rings are pretty much set at .010" and they strongly recommend you don't touch them.

Here are part of the instructions that came with the piston. In italics near the top, not enough gap = engine damage. Line #4 -- oil rings a minimum of .010". Table in the lower right hand corner -- I use the high performance street / strip measurement. A little extra clearance is much better than having the ring tips butt and risking engine damage.

P1040017.JPG
 

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Discussion Starter #19
I followed the directions to a tee and went ever so slightly on the high side for that reason. this thing has the potential to get mighty hot when railed on at low speed.
 

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