Engine Rebuild

[jdizon]

I'm planing to refresh/tune a current running engine for my 78 project. I'm looking at getting upgrading to a 750 bigbore kit and
5th gear overdrive from MikesXS. Aside from the following, What all would you recommend upgrading/replacing during this process?

 

[5twins]

You'll want to do a little work on the head. I recommend cleaning the ports up a bit with a Dremel, lapping the valves so they are leak-free, and replacing the valve guide seals.

 

[jdizon]

Thanks 5twins! I'll add that to my check list. Trying to get one compiled so I have something to follow on the next build.

 

[shotgunjoe]

Probably on your list, but, a new endless timing chain, guides, and elephant foot mod would save you from opening it again for a long time.

 

[TwoManyXS1Bs]

If you open-up the head and cam it, think twice about the exhaust and carbs.

 

[itrguy]

You should rephase....

 

[jdizon]

@Shotgunjoe, Thanks for the info.. I was looking at cam chains and looking at that endless timing chain. What is the advantage of that particular one?

@Twomanyxs, thanks for that info.

@itrguy - Thinking about that as well but I'm not sure I want to wait for the turnaround time. It's either 750 or Rephase. On my other build I'll do both but really want to get one of them on the road before summer.

 

[5twins]

Unless you're incapable of properly installing a rivet master link, I see no advantage to the one piece cam chain. The bike came from the factory with a riveted master link. These bikes have been out there running around for 30+ years with riveted master links. The big disadvantage to installing the one piece chain is you have to disassemble the whole engine to put it in. The crank needs to be freed up so you can slip the chain over one end of it. The rear chain tensioner will also need to be split apart to get the chain through it, and it's riveted together. Personally, I don't feel the benefits (none really) justify all the extra work involved.

 

[VosaME]

It was recommended to me to also do the solid clutch pushrod and new pushrod bushing, I figure might as well do all the upgrades you can when it is apart.

 

[jdizon]

Damn way more involved than installing the master link .. I think I'm going to stick a riveted master link setup. Great information. This is the chain I plan to get from Mikexs

Anything better?

Part #52-4008

Cam Chain - Daido 219FTss x 106 with rivet link. Pitch .3061" (7.774mm.)
Fits: TX/XS650's 1974-84 (36 tooth cam). The latest high strength cam chain
from D.I.D. for late XS650's. Made in Japan.
Also fits: SR500 E/F/G/H 78-81, XT500 C/D/E/F/G/H Dual Sport 76-81

Unless you're incapable of properly installing a rivet master link, I see no advantage to the one piece cam chain. The bike came from the factory with a riveted master link. These bikes have been out there running around for 30+ years with riveted master links. The big disadvantage to installing the one piece chain is you have to disassemble the whole engine to put it in. The crank needs to be freed up so you can slip the chain over one end of it. The rear chain tensioner will also need to be split apart to get the chain through it, and it's riveted together. Personally, I don't feel the benefits (none really) justify all the extra work involved.

 

[5twins]

That one should be fine. That's what most of the originals were. The problem with them wasn't in the quality, it was the lack of maintenance (adjustment). This was partly Yamaha's fault because they didn't spec frequent enough maintenance intervals. You should check the cam chain, and adjust if need be, about every 1000 miles. I've made it a habit to do so at every oil change which is about that. You're running the bike and warming the engine anyway for the oil change. It only takes a minute or two to pop the acorn cover nut off the cam chain adjuster and check it's tension while the bike is sitting there idling. Then shut 'er down and dump the oil.

 

[jdizon]

Thanks for confirming 5twins. I'll add that to my check list when I do my oil changes. Good info for us newbees

 

[shotgunjoe]

The xs came with lots parts which were either a design or price compromise... following this chain of thought over 30 years later just seems silly to me. 5twins, are you also still running points, individual reg/rec, stock carbs, stock charging system too? (granted stock carbs arent really bad... but they are a compromise). Could you say that the split chinese made chain will take the same abuse as an original yamaha part? If its a lower quality part to begin with, its a bigger compromise than the old chain was.

Peace of mind is worth the extra work for me... just my humble opinion.

 

[hotdog]

The daido chain is made in Japan.?
There is nothing wrong with a linked chain, just ensure you pein the link ends correctly.

 

[shotgunjoe]

Most of the repairs ive made on my bike were because the PO, didn't do the repairs correctly in the first place... Hotdog, you are sooo dead on.