79' CB750k Cafe racer.

[sprcrg]

Thanks. I'll have to check this out.

 

[sprcrg]

Well, I've got the new engine here. Took out the old broken one and going to start swapping parts to make a good working one.

 

[sprcrg]

I got the heads off of the new engine. Nice a bloody dirty. But Everything seems to be in working order. The clean cams are the original engine.

 

[sprcrg]

Same as below.

 

[GB400 fan]

im about to rip down my DOHC too and like you I also have two motors so i really hope i have enough good parts to make 1 good one!! kep the pics coming so i can compare and i'll start posting my tear down!

 

[sprcrg]

Well it turns out I broke a connecting rod. I was running very lean and that burned oil then SNAP. So I am just going to continue to clean up the new engine. Wish me luck.

 

[sprcrg]

im about to rip down my DOHC too and like you I also have two motors so i really hope i have enough good parts to make 1 good one!! kep the pics coming so i can compare and i'll start posting my tear down!

Right on Tery. I'd like to see what you've got on the go.

 

[Hoosier Daddy]

Well it turns out I broke a connecting rod. I was running very lean and that burned oil then SNAP. So I am just going to continue to clean up the new engine. Wish me luck.

Damn-it all to Hell!
Sure am wishing you luck!

 

[sprcrg]

Found the problem. Check this out.

 

[GB400 fan]

Wow nasty, thats why i think i'll tear down all the way so i can examine and polish the conrods, thank god for the spare huh!!

 

[sprcrg]

What happened, after examination, was that I bought the bike with the 4-1 exhaust. The problem was that it was never jetted accordingly so it was running mega lean. Shit got hot and, well.... Shit goes bad. Real bad.

 

[sprcrg]

Ok. Looking for anyone who has jetted the DOHC before. I am trying to decide the best jet kit to buy. I was wondering what jets you put in with a 4-1 exhaust. Not looking for a scientific breakdown, just ballparking what I may need. Thanks.

 

[notlob]

The DOHC doesn't usually need rejetting when fitting an aftermarket 4-1 system. Maybe the PO did rejet and thats why its lean. Are you running the stock are box and filter? Also running lean is more likely to melt the top of the piston or burn a valve than break a conrod.

 

[sprcrg]

The DOHC doesn't usually need rejetting when fitting an aftermarket 4-1 system. Maybe the PO did rejet and thats why its lean. Are you running the stock are box and filter? Also running lean is more likely to melt the top of the piston or burn a valve than break a conrod.

So maybe just tighten up the air screw? They were pretty wide open.

 

[notlob]

Standard setting is 1 1/2 to 1 3/4 turns out from seated.

 

[sprcrg]

Well I've got some new gaskets, progressive shocks and Avon roadriders on route for the ol' gal.

 

[sprcrg]

Seat pan in place. Hides the electronics quite well.

 

[seestheday]

The DOHC doesn't usually need rejetting when fitting an aftermarket 4-1 system. Maybe the PO did rejet and thats why its lean. Are you running the stock are box and filter? Also running lean is more likely to melt the top of the piston or burn a valve than break a conrod.

I agree. I would look for oil delivery issues. Have you checked your oil pump and oil screen?

Also, since you have the head off and cams out, are you planning on putting in some cb900 cams for the nice mid-range performance bump? Probably the cheapest and most effective performance bump you can do.

 

[Hoosier Daddy]

SEES!!!!
Welcome to the coolest forum on the interwebz!!!!

 

[sprcrg]

A few more tweeks and I'm ready to rock. 8)