350F rebuild

[silentsvn]

Trying to weigh the options of doing a rebuild myself or letting a shop do it.

Recently after working out some clutch issues I ran the bike pretty hard for about 50 miles on a 80m round trip and she started to puke oil out of the head gasket and the lower crank gasket.

The #4 plug well was full of oil and there was spray all down the back of the bike. So Im wondering if letting a shop do the rebuild or not.

 

[Hoosier Daddy]

1.) How deep is your wallet?
2.) How mechanically inclined are you?
Before turning my bike over to someone else, I would definately get a "not to exceed" amount quoted instead of just an open checkbook to a REPUTABLE shop. But I have been inside several engines in my life and kinda got a good grasp on how things work. A head gasket and base gasket isn't that bad of a job...So I'd tackle that one myself.

 

[silentsvn]

I'm a pretty good wrench.

I'm more worried about the "can of worms" contingent. The bottom end seems good the top is just a bit bulimic.

 

[SONICJK]

That motor looks fine and I would by no means call any part of it covered in oil
It probably just needs new rings and these things are known for head gasket leaks.
Get you a service manual and go to town, its not a complicated engine at all, especially if you don't get into the bottom end!

 

[silentsvn]

All the oil is on my pants plus I just changed it. But trust me it was covered.

The motor is good runs solid I just think it's got a case of the notorious 350f head leaks. So I was just thinking if I have it all apart might as well. But you're right I think gaskets and rings are a must and in my very near future.

Order has been made for both.

 

[ronnie]

The head is easy to take off, 10-15 mins.. It will take you longer to take carbs off and plugs out. I'm not sure if you can do this in frame or not. My engines were both out. But when you do take the head off, bring the head to a machine shop and tell them to "surface" the head. This will take as little metal off as possible while giving you a true surface on the bottom of the head. These heads are known for their leaks in the head gasket. its due to the warping of the head over time from the heat/cool cycles. The re-surfacing will fix that. Get a new gasket and some Threebond and bolt it back up to spec(in manual). It is very trivial but the surfacing will increase compression which will be slight so no big deal or gains there..

 

[silentsvn]

The head is easy to take off, 10-15 mins.. It will take you longer to take carbs off and plugs out. I'm not sure if you can do this in frame or not. My engines were both out. But when you do take the head off, bring the head to a machine shop and tell them to "surface" the head. This will take as little metal off as possible while giving you a true surface on the bottom of the head. These heads are known for their leaks in the head gasket. its due to the warping of the head over time from the heat/cool cycles. The re-surfacing will fix that. Get a new gasket and some Threebond and bolt it back up to spec(in manual). It is very trivial but the surfacing will increase compression which will be slight so no big deal or gains there..

Thanks for the tip - I think I can do it on the bike which will save some time/money. I have seen a few pic's floating around of guys removing the head.

I ordered a complete gasket set from DCC.

 

[ronnie]

Yea no problem, but I highly recommend getting the head resurfaced.. It might coat you 60 bucks, could be cheaper.. Good luck.

Sent from my Galaxy Nexus using Tapatalk 2

 

[silentsvn]

Yea no problem, but I highly recommend getting the head resurfaced.. It might coat you 60 bucks, could be cheaper.. Good luck.

Sent from my Galaxy Nexus using Tapatalk 2

So I got a quote for $80 1 Day turnaround. No one wants to deal with a motorcycle engine apparently.

Should I do a leakage test on the valves before taking to the machine shop? Also should I / do I need to remove the valves?

 

[ronnie]

I'm not sure if you need to or not.. That's up to the shop. I would imagine they wouldn't get in the way if they are just mounting it on a mill. I would leak test it after and lap the valves if you need to before putting it back on.

Sent from my Galaxy Nexus using Tapatalk 2

 

[silentsvn]

Just popped the top - way easier that I thought it was going to be.

Here are some of the pictures.

 

[SONICJK]

Told ya it was simple 8)

But I don't see a blown head gasket....could maybe have just retorqued to stop the leak ;D

 

[silentsvn]

Told ya it was simple 8)

But I don't see a blown head gasket....could maybe have just retorqued to stop the leak ;D

Ya the gasket seemed okay although the underside was soaked in oil.

I guess it will be piece-of-mind.

Valves and pistons were super oily as well as you can see.

 

[SONICJK]

Get yourself some rings,
measure the bore
measure the ring gap
make sure you replace the O-rings on the little oil nozzle things on the sides of the head (not sure what they are called, but they are a big cause of leaks on these things.
hone the cylinders
flatten the head
(maybe check the valves for sealing since you've got them in front of you)
reassemble 8)

 

[silentsvn]

Get yourself some rings,
measure the bore
measure the ring gap
make sure you replace the O-rings on the little oil nozzle things on the sides of the head (not sure what they are called, but they are a big cause of leaks on these things.
hone the cylinders
flatten the head
(maybe check the valves for sealing since you've got them in front of you)
reassemble 8)

Ya I have seen people talk about the o-ring nozzle things on either side of the head being a big source of leaks.

Can I re-use the stock pistons and ring size if I just hone the cylinders?

 

[SONICJK]

Most likely yes.
You need to measure your bore (or have a machine shop do it if you cant) to determine if you can still use STD size rings and pistons or if its worn out past the limits.
Look in the service manual for the limits.

 

[silentsvn]

Okay cool, thanks for your help.

I'll take the cylinders and head to the shop and get them to measure the bore. I don't have a bore gauge only a micrometer.

 

[SONICJK]

Okay cool, thanks for your help.

I'll take the cylinders and head to the shop and get them to measure the bore. I don't have a bore gauge only a micrometer.

Same boat here, i figure I can get the shop to measure 100+ bores before I can buy a good bore gauge haha.

 

[silentsvn]

Dropped everything off. They are going to surface the head, hone the cylinders and deck the cylinders if they need it and of course clean the years of shit off the parts!

 

[SONICJK]

Sweet.
You work fast amigo!

How much for all that if you don't mind my asking?