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Tillerman6

74 TY 250A PISTON & RING ISSUES

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20 hours ago, b40rt said:

A broken engine mount will cause a lot of vibration ......

I could not see the engine moving around in the frame while it was running, and all the bolts were still tight when I removed the engine, so it was still locked in on 5 of the 6 mounting points even though the top right ear was loose from the frame at it's base.   And you are right,  Any loose mounting point is one too many. But the wobble in the magneto housing was the kicker for me.

I am betting that B&J will find something out of alignment with the crank itself. Also it will be nice to finally get closure on that missing needle bearing roller that I never could find.

 

Today I stripped the old paint off the swing arm and painted it.  Then I stripped most of the paint off the frame, but I ran out of energy before I could finish that one. There are a few places where I can't get my wire wheel into close enough to get 100% of the old paint off.  I guess it's Naval Jelly time.  The frame itself had no other cracks, but the bottom race in the headstock will have to be replaced as it was pitted from corrosion/rust.  I did not notice that the head stock was binding or anything, but with the forks removed, you could feel a little roughness while rotating just the triple clamps by hand. It's great that so many of the parts are available on Ebay for this bike!

 

Now I'm trying to get the dimensions for the bottom bearing race itself. The previous owner swapped out the forks for some made by another company.  So I can't tell if the head stock tube bearings are still Yamaha or not. The center pivot tube in the triple tree  is 30mm at it's baseOD where the bearing is bad, The bearing I have on this bike is  a30mm ID and a  47.6mm OD. but of course there are no dimensions in the parts list, only part numbers. in this case it is 156-23411-00. I have this question in to a couple of dealers on Ebay, and maybe one of them will measure what they have and let me know. 

I also want to do something about  changing out this stock air box and handle bars.  The air box outlet pipe is too far away from the carb and the plastic hose is therefore pretty fiddly to gt it to make a good seal.  I really don't like the air box itself- heavy , awkward and hard to get the air filter set in place just right. Thinking of going to a K& N sock, but still need some protection from water ingestion. Any ideas?

I am also removing the old front fender and brackets. Going to a trials bike setup. The lights and brake light switch are coming off. The seat will also be replaced when and if I ever go trials riding.

This is turning into a 2K play bike, but I'm enjoying the changes.  It's only money and I don't chase women, so what else am I gonna do with my few remaining years!

 

And- someone was on here talking about mounting some larger handle bars.  I think that is also needed.  Especially if the foot pegs are mounted to the rear position. But I have not seen any handlebars that have more rise than standard.  Any ideas there?

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I bought I of those for my TY, perfect fit on the bike & well worth the money

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14 hours ago, lineaway said:

 Find a rubber boot for the air box. A sock is not going to make it run better, in fact probably worse.

Reproduction. https://www.ebay.com/i/112480199125?chn=ps

Lineaway, (or anyone?) did you notice the boot being too short on any of your TY's?  What's exasperating is that they want an arm and a leg for that new boot and you might get one and it would be too short just like the old one!  Arrgh!  I might go back to the autoparts store and look thru what they have in the way of a radiator hose, there might be something that could be cut down  or cut off one end. Most of their stuff is not so extravagant.! The other thing is that I might get a new carb soon and it would probably be different than the old JK that is on there now. I think that is the case with the carb I have been considering the OKI I think it is.

 

Paint- Still working on cleaning off all the old paint. There was zero primer under that (what I think was the original paint) , so most of it comes off pretty easily. Today I used a You tube trick that one guy did by making a mini air blaster from a Harbor Freight air gun and some walnut shells inside a soda bottle.

3 minutes ago, tony27 said:

I bought I of those for my TY, perfect fit on the bike & well worth the money

So did you break your old one, or why did you replace it? Was it too short and is the new one slightly longer?

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Thing is I need so much stuff for the bike and all at once. Tires, throttle, handlebars, foot peg work, paint, engine work, postage, a seat base and seat cover,  a new front fender bracket and a new front fender. Probably a new rear fender too.

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4 minutes ago, lineaway said:

After 40 years the rubber shrinks. Happens to most brands.

Do you know anything about paint?  I am really tempted to use just a galvanizing paint in a spray can that I stumbled on while doing some welding work last year. This stuff is about 50% zink, but it goes on thin and evenly. dries in about 3 minutes. is fairly tough and fights rust to the bitter end. You can touch up any scratches with just an extra squirt of the stuff and it is a medium silver color.

I painted my home made rear bumper on my old pickup  with the same stuff and it is holding up thru the winter really well. The best thing is that if you do get some rust somewhere from a scratch or whatever, you just sand off or wire brush off the rust and spray again. Assuming that you can get to the area in question, you are done in about 30 minutes and dry to the touch in 3 minutes or less. This stuff also seems to stick and flow down onto the metal really well too.

 

I went to a powder coating place today just to see what they could do and they wanted $150.00. Probably worth it, but the zink paint can be patched at home.

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Zinc-rich-primer (used for painting welds on galvanised structural steel) usually has a matt finish that is pretty much impossible to keep clean. 

I paint my frames with automotive lacquer for the same reason you mentioned - it is very easy to touch up the inevitable scratches, but it looks good, unlike the zinc spray paint

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On 4/23/2019 at 5:22 AM, mcman56 said:

I recently rode a TY175 with the B&J full engine mods.  I don't know what all of the mods are but performance was extremely impressive.  More power everywhere, much better response yet still silky smooth and pulls to extremely low rpms.  I have ridden a TY with modified frame and another that was ported but they seemed at most a little different from stock.  This was a whole different animal.        

 

On 4/21/2019 at 9:31 AM, mcman56 said:

Like he said.  I believe they are the US experts on this.

 

Well it's been April 21 to July 11. My lower engine cases were sent to B&J racing in Tennessee for a look see.

After all that time- no joy. The owner said he didn't have time to put the crank in his lathe and check it out completely and he doesn't know where the metal chips he found inside came from.

Apparently it was not a good time to send my engine to him. He had some serious family child illness and several trials events occurred during that time, so I guess I can't be too unhappy about the delay, but not having any idea about when my engine would be fixed was too much for me. They are super busy.

So I am having him send me back the engine as is. They also did not find any pin from the needle bearing inside, so at least it was not in there doing nasty things to the innards.

I am going to withhold judgement on B& J until I see what's been done and what I can do to fix it myself.  If there is not too much damage, I will be trying to fabricate or borrow the tooling needed to re-assemble the engine case halves.

If anyone has done this operation with the factory tools or equivalent, I would very much like to hear about the process and the tools needed.

 

 

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On 4/25/2019 at 7:55 PM, feetupfun said:

Zinc-rich-primer (used for painting welds on galvanised structural steel) usually has a matt finish that is pretty much impossible to keep clean. 

I paint my frames with automotive lacquer for the same reason you mentioned - it is very easy to touch up the inevitable scratches, but it looks good, unlike the zinc spray paint

I went ahead and used the automotive paint on most of the frame. Should have sanded it more. A little rough to the touch now. But that's the least of my problems with this bike. The engine has been in limbo at B&J racing since April, so I'm having him send it back to me AS IS. I don't think I will worry about the paint if the engine is toast.

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On ‎4‎/‎26‎/‎2019 at 1:47 PM, Tillerman6 said:

Lineaway, (or anyone?) did you notice the boot being too short on any of your TY's?  What's exasperating is that they want an arm and a leg for that new boot and you might get one and it would be too short just like the old one!  Arrgh!  I might go back to the autoparts store and look thru what they have in the way of a radiator hose, there might be something that could be cut down  or cut off one end. Most of their stuff is not so extravagant.! The other thing is that I might get a new carb soon and it would probably be different than the old JK that is on there now. I think that is the case with the carb I have been considering the OKI I think it is

So did you break your old one, or why did you replace it? Was it too short and is the new one slightly longer?

The wasn't a standard airbox fitted when I first got the bike to work on, the A model I could rob parts off if needed had a shrunken, rock hard connection. Once I got a C model airbox I needed a connection & I found the seller on eBay was making them. Their website is www.claussstudios.com  well worth a look for rubber parts for other model bikes 

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Quote...  I went to a powder coating place today just to see what they could do and they wanted $150.00.

I know some people like powder coating, but I avoid it like the plague, because once the water gets behind it through a crack or chip, it corrodes the metal from within. 

So in a couple of years time it can totally rust through a frame tube, unseen by anyone.

.

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On 7/13/2019 at 4:31 AM, tony27 said:

The wasn't a standard airbox fitted when I first got the bike to work on, the A model I could rob parts off if needed had a shrunken, rock hard connection. Once I got a C model airbox I needed a connection & I found the seller on eBay was making them. Their website is www.claussstudios.com  well worth a look for rubber parts for other model bikes 

Tony- Thanks for that input, but I found that just by warming up the rubber coupling with a hair dryer it comes back to life and you can still use it. - Don't get it too hot, but even warm water should be enough to soften the material and it becomes stretchy and not prone to crack again.  Good luck!

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On 7/13/2019 at 9:22 AM, scifi said:

Quote...  I went to a powder coating place today just to see what they could do and they wanted $150.00.

I know some people like powder coating, but I avoid it like the plague, because once the water gets behind it through a crack or chip, it corrodes the metal from within. 

So in a couple of years time it can totally rust through a frame tube, unseen by anyone.

.

Duly noted and I ended up spraying it myself with automotive paint.  Glad I didn't powder coat after all! Thinking of following that with a clear coat before re- assembly if I ever get the engine back and back together. Arrrrgggghhh!

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If you want your engine fixed pm me and i will give you my phone number.For example stealth performance in eagle river wi does exceptional crank work and is fast.I know of no one including B&J performance that jas actual aftermarket pistons(he modifies dt pistons which works fine)There are various pistons that work in the ty.Yours appears to be a yz the same as my wossner.Same basic specs but yami went to fly cut for better breathing on yz models.You can go over to adventure riders and check out my build thread in trials section.Have not updated the one here.

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