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Old 07-27-2014, 07:14 PM   #16
LashLarue
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Not enough

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Originally Posted by Sidecar Jockey View Post
I put the bike in grer and rolled it around while trying to shift into low. All it does is make the ratcheting click. 'High' works fine though.
It will make that noise when it is not far enough to engage. Spin the back tire and press a little higher.

Or just wait. No one uses low except in extra ordinary circumstances. High gears, first gear is just fine for 5 mph. Low First is for 1 mph.
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Old 07-28-2014, 04:40 AM   #17
Sidecar Jockey OP
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I took the top end off of my locked up motor this weekend and found that the rings were rusted to the cylinder. I had to use heat and drive the piston out. The good news is that the crank feels smooth and looks good.

While my spare motor turns over freely, its low on compression. It also wont click into every gear and it sounds like there is a good bit of metal stuff rattling around in the crank case / tranny. Not good. I'm going to use this one as a parts motor, since I dont feel like splitting the cases and I think my other motor is in better shape.

I'm going to order the 54mm big bore piston from DR ATV, and have a local machine shop fit it to the cylinder. The cylinder damage isnt too deep, so I'm sure a 4mm overbore should straighten it out.
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Old 07-28-2014, 10:02 AM   #18
ADVDucs33
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Sounds like some nice progress on your '69! Are the valves in good shape still? I just received new tires for mine, bikebandit, tires were 26 ea, tubes 7 :) just incase you need some down the road, wayyy cheaper then fleabay.
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Old 07-28-2014, 12:56 PM   #19
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Originally Posted by ADVDucs33 View Post
Sounds like some nice progress on your '69! Are the valves in good shape still? I just received new tires for mine, bikebandit, tires were 26 ea, tubes 7 :) just incase you need some down the road, wayyy cheaper then fleabay.

The valves and rockers look like they are in good shape. The bike with the seized motor only has 1,600 originam miles on it, so I doubt it needs head work.

Plus, I cant figure out how to get my normal sized valve spring compressor into this tiny head...

The Dr ATV 53.5 mm piston is ordered. $39!! Thats the cheapest piston I have ever bought! Does anyone know what clearance to bore the cylinder to for the DR ATV pistons?? Thanks.
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Old 07-29-2014, 08:37 AM   #20
redprimo
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Wicked

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Originally Posted by Sidecar Jockey View Post
The valves and rockers look like they are in good shape. The bike with the seized motor only has 1,600 originam miles on it, so I doubt it needs head work.

Plus, I cant figure out how to get my normal sized valve spring compressor into this tiny head...

The Dr ATV 53.5 mm piston is ordered. $39!! Thats the cheapest piston I have ever bought! Does anyone know what clearance to bore the cylinder to for the DR ATV pistons?? Thanks.
The manual calls out for .004" clearance on the stock piston. There should be specs inc kidded with the new piston and of it is forged it could call put for a tighter fit. I think I did my last 54mm CT build with a .0025" piston clearance.

The longer duration cam that dratv sells is a nice compliment to the 54mm piston, even with the stock carb.
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Old 08-02-2014, 07:59 PM   #21
lesman
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I"think" there are orings in or around the valve guide that tend to go bad with age.
The bike will smoke if they aren't replaced.


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Old 08-04-2014, 04:04 AM   #22
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Originally Posted by lesman View Post
I"think" there are orings in or around the valve guide that tend to go bad with age.
The bike will smoke if they aren't replaced.


Les
Are these 'o-rings' in the valve guides like valve stem selas?

I'll have to check into that, thanks. I wasnt planning on doing anything to the head, since my normal sized valve spring compressor is too big to use on this tiny head... but now I'll need to figure something out.


The Dr ATV big bore piston (53.5 mm) didn't come with any info. I dropped the piston and cylinder off at the machine shop on Friday, and the machineist said that he will contact Dr ATV and get the boring specs. He quoted me $100 to bore the cylinder and fit the rings, which seems like a fair price.
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Old 08-04-2014, 04:44 AM   #23
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Quote:
Originally Posted by Sidecar Jockey View Post


The Dr ATV big bore piston (53.5 mm) didn't come with any info. I dropped the piston and cylinder off at the machine shop on Friday, and the machineist said that he will contact Dr ATV and get the boring specs. He quoted me $100 to bore the cylinder and fit the rings, which seems like a fair price.
That price is high in my opinion. You should take him the head too and have him resurface the valves and seats. all included for $100 would be about fair.


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Old 08-04-2014, 08:01 AM   #24
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Originally Posted by Cogswell View Post
That price is high in my opinion. You should take him the head too and have him resurface the valves and seats. all included for $100 would be about fair.


Mike

I wish. All of the machine shops in my area are crazy epensive. They all must be in on the price fixing together or something, because they all charge about the same price, do average work, and take a week too long to do it.

I might try out one of those "mail me your cylinder and piston and i'll bore it" guys on Ebay next time...
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Old 08-05-2014, 10:03 PM   #25
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Quote:
Originally Posted by Sidecar Jockey View Post
Are these 'o-rings' in the valve guides like valve stem selas?

I'll have to check into that, thanks. I wasnt planning on doing anything to the head, since my normal sized valve spring compressor is too big to use on this tiny head... but now I'll need to figure something out.


The Dr ATV big bore piston (53.5 mm) didn't come with any info. I dropped the piston and cylinder off at the machine shop on Friday, and the machineist said that he will contact Dr ATV and get the boring specs. He quoted me $100 to bore the cylinder and fit the rings, which seems like a fair price.
Your bike only has one valve guide seal on the exhaust, the intake valve dissent have a seal. If you get the Vesrah gasket set it is included. The oil seals for the kick starter, gear shift, primary shaft, cam shaft, or sub Trans shaft are not in the Vesrah set but dratv does sell them aa set. You really should make an effort to replace the valve guide seal. After 45 years it gets pretty brittle regardless of how many miles the bike has on it.

I use a c clamp and a block of hard wood I made for that purpose to compress the springs. Not ideal but it works.
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Old 08-06-2014, 10:01 AM   #26
ADVDucs33
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Question

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Originally Posted by redprimo View Post
Your bike only has one valve guide seal on the exhaust... You really should make an effort to replace the valve guide seal. After 45 years it gets pretty brittle regardless of how many miles the bike has on it.

If this seal were to crumble apart and go ca-puttz, would leaking fluids and loss of compression be the result? Like Sidecar, I think I have to tear into my little 90 as well.

Thanks!
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Old 08-06-2014, 10:19 AM   #27
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Quote:
Originally Posted by ADVDucs33 View Post
If this seal were to crumble apart and go ca-puttz, would leaking fluids and loss of compression be the result? Like Sidecar, I think I have to tear into my little 90 as well.

Thanks!

It would NOT cause an external leak or loss of compression. It would allow oil to get sucked down the valve stem and into the combustion chamber, resulting ain LOTS of blue amoke when the motor is running.

The good news is that it takes me about 15 minuts to take the top end off of a trail 90. Its the easiest bike I have ever worked on.
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Old 08-06-2014, 02:43 PM   #28
redprimo
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Quote:
Originally Posted by Sidecar Jockey View Post
It would NOT cause an external leak or loss of compression. It would allow oil to get sucked down the valve stem and into the combustion chamber, resulting ain LOTS of blue amoke when the motor is running.

The good news is that it takes me about 15 minuts to take the top end off of a trail 90. Its the easiest bike I have ever worked on.
The valve guide seals rarely crumble. Usually the crack and leak but stay in place.

The death of most of these engines is oil starvation of the top end due to a clogged oil screen or oil passage. Change the oil often and swap the 40+ year old clutch for a fresh one ( a 40 year old clutch is prone to disintegrating and creating lots of crud that clogs the oil screen) and you should have no problems getting 10-20k.
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