Dazed and Confused

Does sound like a valve issue.

Patton wrote:

moneypit wrote:

I rebuilt my 76 900 motor last winter bored to 1015,
new rings, head (ebay buy) checked by local shop,
they said it was fine, finnally get it togeather and NO compression on #3 NOT ANY PERIOD. Oil down the plug hole NO change. Compression checked just by putting thumb over plug hole. Lost my comp tester to thief:angry:
I can see the valves and they look good (thruogh the plug hole) Pulled cover today and cams and buckets look
good. #3 exhaust bucket rotates when turning over with
kick lever and can spin the bucket when lobe is away from shim, valve clearances may be a little tight over all .03mm on that shim. Changed coils on that cyl. no change,
Changed carbs from 29 smoothbores to 26s still no
change
Help $$

NO compression on #3...#3 exhaust bucket rotates when turning over with kick lever and can spin the bucket when lobe is away from shim....

What about the intake clearance? Is there at least some minimal clearance on intake #3? Just wanting to confirm.

Would consider taking a ride "on three cylinders" with idea of possibly blowing away any carbon speck that might be interfering with complete seal of a #3 valve seat.

Am also wondering whether the local shop was correct when opining that the head was fine. Was each valve checked to assure it fully sealed in the seat when closed?

Good Luck!

There is clearance on the intake too Im not sure of the exact amount offhand. Id like to ride it but no tabs at this time and it hasnt been on the road since 96?
so tires are hard not cracked but I wonder and just triing to get things done a little at a time still need some carb tuning it will rev and idle fine on 3 I wonder if I buggered a valve some how but man I was as careful as I could be Thanks all Bob$$

With #3 at TDC, pump compressed air into spark plug hole while listening for escaping air at exhaust outlet and at carb intake.

This should help identify which valve is failing to seat.

Good Luck!

Patton wrote:

With #3 at TDC, pump compressed air into spark plug hole while listening for escaping air at exhaust outlet and at carb intake.

This should help identify which valve is failing to seat.

Good Luck!

Yeah I want too do that but Ill have to get the adapter for the plug hole/compressor mine was stolen along with 5 bills worth of tools

Pic of cam timing

I had new valves installed last year and after I put the head back on I hooked my compressor up and did what Patton suggested. It sounded like a hurricane coming out of the number one exhaust valve. I could see the valve and it looked closed. I pulled the head off and took it back to the guy who did the valves. There was a speck of something, looked like a thin paint chip, on the valve seat. He flicked that off and relapped the valve and it was fine. I was surprised how much air came out due to such a small thing on the valve seat. It really sounded like the valve was completely open.

moneypit wrote:

...have to get the adapter for the plug hole/compressor mine was stolen along with 5 bills worth of tools

Could just use a rubber tipped blowgun held pressed into the plug hole.

Am thinking perhaps nothing buggered in reassembly, but erred in relying solely on the shop's opinion without bench testing for proper valve seating before installing the head.

Good Luck!

I do believe they lapped them they better have for 400 bills

moneypit wrote:

I do believe they lapped them they better have for 400 bills

OUCH! Was that just for a valve job or was it ported, new valves, guides.....etc?

Patton wrote:

Am also wondering whether the local shop was correct when opining that the head was fine.

My job requires that I read title opinions all day written by attorneys, I have not heard any one else use the word opining before.
I really have nothing useful to add.

I thought it was a typo! :laugh:

opining - Collaborative International Dictionary of English:

Opining \O*pin"ing\, n.
Opinion. [Obs.] --Jer. Taylor.
[1913 Webster]

Opine \O*pine"\, v. t. & i. [imp. & p. p. Opined; p. pr. & vb.
n. Opining.] [L. opinari, p. p. opinatus; akin to opinus
(in comp.) thinking, and perh. to E. apt: cf. F. opiner.]
To have an opinion; to judge; to think; to suppose. --South.
[1913 Webster]:Opining: The act of thinking of an opinion.

To each thier own :laugh:

larrycavan wrote:

moneypit wrote:

I do believe they lapped them they better have for 400 bills

OUCH! Was that just for a valve job or was it ported, new valves, guides.....etc?

Nope just looking them over and seeing which was best I actually gave them 2 heads to check I should have sent them to you Larry :blush: