Starting a top end refresh on my 225DR..any shortcuts or suggestions.

[dougspcs]

Well I have gotten pretty good at the whole top end rebuild thing lately..just finished my second yesterday.

144613144614

So I picked up a Black 225DR that is in decent shape, but it smokes and the compression is a bit low. Just shy of 110PSI..

I figured I could tackle that and ordered up the parts, then printed and read over the manual section on engine. Seems pretty simple and the bonus is this one looks like it can be done in bike, though a little tight it will be nice not to have to bench the engine.

Anyway, are there any hints/tips/cautions on this engine??..and yes I know. DON'T forget the oring!!

[El Camexican]

Well I have gotten pretty good at the whole top end rebuild thing lately..just finished my second yesterday.

144613144614

So I picked up a Black 225DR that is in decent shape, but it smokes and the compression is a bit low. Just shy of 110PSI..

I figured I could tackle that and ordered up the parts, then printed and read over the manual section on engine. Seems pretty simple and the bonus is this one looks like it can be done in bike, though a little tight it will be nice not to have to bench the engine.

Anyway, are there any hints/tips/cautions on this engine??..and yes I know. DON'T forget the oring!!

Hi Doug,

I’ve done two 200’s (same engine as the 225 as far as I know) You should be able to do everything with the engine in the frame. My suggestions are that you only bore the cylinder as little as possible as I think the 200 and 225 share the same jug and while the 200 can be bored many times the 225 might already be punched out from the factory. I’m not sure of this, but suspect it is the case. Another thing is the cam chain timing. Having bent a valve my first time into one of these engines I was very careful on the second one and found that the timing marks are “sloppy” in that it seems like you can be off a tooth and the marks still almost line up and if you do have it right they still don’t seem to line up perfectly. I’ve read that other people say they had no issues, so maybe it’s just me or maybe it was the trikes (sequential serial numbers). If you are burning oil you’ll want to change the valves, the valve guides and the seals. Make sure you get the compression release assembly back on correctly (if this engine has one) and I suggest you change your cam chain as well and reset it every 10 hours or so for the first 30 hours of use. And finally, when you have the intake and carburetor off the head take a good look at the diameter of the intake port of the head, the exit hole of the manifold, the entrance hole of the manifold and the carburetor diameter. I’m guessing you will be tempted to do some port matching, but be careful as my first attempt ended up with a cracked manifold as I removed too much material.

[dougspcs]

I don't think I will do anything with piston. This small amount of compression loss shouldn't see too much damage, I will probably see if I can get away with just hone and ring job. But will replace the valve guide and seals since I have a spring compressor now.

I will consider the chain at the same time since that is pretty cheap insurance.

Thanks

[El Camexican]

I don't think I will do anything with piston. This small amount of compression loss shouldn't see too much damage, I will probably see if I can get away with just hone and ring job. But will replace the valve guide and seals since I have a spring compressor now.

I will consider the chain at the same time since that is pretty cheap insurance.

Thanks

I'll bet your cylinder is in pretty good shape as long as it always had an air filter in it. Mine hardly had a ridge and it was run with water in the crankcase a lot. It also had literally thousands of miles on it. The bottom ends on those things are amazing as well.

[dougspcs]

The bottom ends on those things are amazing as well.

Good to know because I got a YTM200E that has a terminal knock that I think is top end(my hearing isn't the best)..I was considering tearing it down but wasn't sure how far it might go..don't really feel like doing a case slipt it just isn't worth the work. Plus I could double my money in parts alone!!

Maybe a winter project since the rest of the trike is in good shape and I got it for peanuts.

[dksix]

I got my 225DX out yesterday and rode it a little, it's time for it to be freshened up. If you had time, I'd be interested in a detailed thread on this. Not necessarily a complete how to but maybe the parts, prices and pics of the basic steps.

[El Camexican]

Good to know because I got a YTM200E that has a terminal knock that I think is top end(my hearing isn't the best)..I was considering tearing it down but wasn't sure how far it might go..don't really feel like doing a case slipt it just isn't worth the work. Plus I could double my money in parts alone!!

Maybe a winter project since the rest of the trike is in good shape and I got it for peanuts.

My ears are bad too. Try taking a wooden hockey stick handle and pressing it to the engine at one end and against your ear with the other while it’s running. You’ll find the source of the knock/tick very easily as you move it to different spots. My 200 engine ticks like crazy at the exhaust valve. It drives me nuts, but as one of my mechanically inclined friends pointed out, it’s the only engine I own that isn’t water cooled or making so much exhaust noise that I can actually hear the engine. I've checked and adjusting the valve a number of times and it just won’t go away, so I live with it. For what it’s worth I do recall that properly adjusting the cam chain on that engine can make it a bit quieter too.

[atc007]

All great advice except , Do NOT touch the valve guides!!!!!!!! Do not touch them . Getting the new ones in straight is tedious,and ALWAYS requires a regrinding of your valve seats. ALL completely unnecessary. Inspect your piston carefully,,I WOULD replace it,more than likely over bore,,but that is a call your cylinder will make. If it's smoking you will almost always find scratches/gouges in the intake skirt,,these lead to cracks very soon. Do a valve job{ clean and lap} NEW seals. Forget the guides. In 24 years I have never seen a guide that needed replaced,other than broken ones from grenading. With new seals you will Never seep oil down the guides on these bikes. It is all done in the frame,the rockers come out after you " pull" the rocker shafts out w a GOOD quality bolt!. Some are Really ! in there,some come right out. Watch the O ring on the oil push stud! Post back w any questions,although I won't be on here a whole bunch for awhile.

[dksix]

I've got to start working on my own engines. I know how, understand how everything works and works together but after I've spent the money for new parts I don't want to make a mistake and have to respend all that money again. I pull the engine, tear it down, decide what needs replaced, order all the parts, take parts to the machine shops to have that part of the work done and when I have everything right and ready to go back together I take them to a local indie shop and have him put it all back together.

[El Camexican]

All great advice except , Do NOT touch the valve guides!!!!!!!! Do not touch them . Getting the new ones in straight is tedious,and ALWAYS requires a regrinding of your valve seats. ALL completely unnecessary. Inspect your piston carefully,,I WOULD replace it,more than likely over bore,,but that is a call your cylinder will make. If it's smoking you will almost always find scratches/gouges in the intake skirt,,these lead to cracks very soon. Do a valve job{ clean and lap} NEW seals. Forget the guides. In 24 years I have never seen a guide that needed replaced,other than broken ones from grenading. With new seals you will Never seep oil down the guides on these bikes. It is all done in the frame,the rockers come out after you " pull" the rocker shafts out w a GOOD quality bolt!. Some are Really ! in there,some come right out. Watch the O ring on the oil push stud! Post back w any questions,although I won't be on here a whole bunch for awhile.

My valve guides were worn and so were my stems, so I replaced the works. I had the guides reamed and the seats cut. It’s an all or nothing deal once you go past just changing the seals and lapping the valves. Nothing wrong with just doing that like you said, IF the guides aren’t loose, but mine were bad. I replaced the springs as well.

[atc007]

Wow. That's uncommon! I know youre advice is awesome, just very unusual you needed all of that.

[dougspcs]

Alright me again..more Yamaha questions.

So I got the top end off..this much I like about the Yamaha over the Honda. I didn't have to take the engine out.

But there is some pitting in the cylinder, looks like water sat in one spot and formed a corrosion point in the wall. Anyway I honed it and it's still visible and you can feel it with your thumb nail.

So I guess it's bore and new piston time..how far oversize can the cylinder go? What is a good piston kit to use??

I'm kinda feeling good about this one!!

http://www.ebay.com/itm/YAMAHA-YTM225-WISECO-PISTON-50MM-OVER-YTM-225-84-88-/290422939715?pt=Motors_ATV_Parts_Accessories&hash=item439e8e6043&vxp=mtr

Is there anything else I need to do with this engine if I go with the higher compression kit?