Topic: Belfast-2-Belfast-By-Bike: Part 3

[Don R]

 I can't tell by the sound but my old race motor has stretched primary chains (70mm) and it makes a crazy noise. That doesn't explain the catching at TDC however.

[The Lone Builder]

Spent quite a bit of time on Sunday morning trying to adjust valves to get rid of that "sticking point". Also checked for oil at the top even though I was sure thee passages were clear and pressure good.

I knew the passages were clear because the oil I poured over valves and cam during assembly ended up on he floor as eat oil hoses were not connected! 

No 4 exhaust seemed to be the main culprit in the stickage (?) so I adjusted it. When finally free, the gap was >0,3mm (0,012"). I don't know exactly what it was because I couldn't get a larger feeler gauge in; the 0,3 gauge had plenty of room though.

Reasoning tha this wasn't going to work for long, I started thinking of options and coming up with nothing that sounded reasonable, I called Honduran for some advice. Mark agreed that my head was probably useless - most people wouldn't be surprised about that  – and that 2 head gaskets wasn't the way to go.

He just happened to have, to hand, a head that he had already worked on and was ready to fit. SO now that is on its way to me and I am in the process of taking the engine out again.

So when disaster strikes, just remember, "It'll be all right in the end, and if it's not all right, it's not the end!" The Belfast Odyssey continues! 

[PeWe]

Fantastic that you can repair on your tour very far away from home.
A real adventure.

I'm curious about that head's height.
How much that was shaved off.
It is very easy to get the cam chain a tooth wrong too.
Important to rotate engine a few turns without plugs after assembly  to double check the markings, crank vs  cam when tensioner is mounted. I learned that the hard way 40 years ago.
No damage, only ticking sound at start-up. Engine went out direct....

[jaytee-nz]

Sean, I'm 400 km's away from you but if I can help in any way please let me know.
Unfortunately, I don't know anyone in Auckland who could assist you (it's a city I try to avoid!).

Cheers - John (JT)

[The Lone Builder]

Well  took the engine out and removed the rocker cover.

As PeWe suspected, the cam chain was one tooth off. I have corrected that and set the clearances as per the manual. The engine turns over smoothly now.

Question is whether the previous interference has bent the valves. If I take the head off and remove the valves, would I be able to see if they were bent?

Would checking the compression give the same answer?

[The Lone Builder]

Sean, I'm 400 km's away from you but if I can help in any way please let me know.
Unfortunately, I don't know anyone in Auckland who could assist you (it's a city I try to avoid!).

Cheers - John (JT)

Thanks John.

My plan, once back on the road is to head south down the east side, over the South Island and then when coming back go up the west side of North Island.

I'll give you a shout as I approach New Plymouth; or sooner if I need more help! 

[jaytee-nz]

Low compression might indicate a bent valve but the only way to know for certain is to remove the valve. If you have the use of a drill, put the valve in it and see if it spins without a wobble.

Sounds like a plan, so give me a shout when you are coming my way.

[The Lone Builder]

That sounds like a plan. Tomorrow I can get a compression tester. If all cylinders are equal and reasonable, I'd say good to go.

If one is much less than the others, then I'd have to take that one out and check it.

I know this is a rough approach, but what else?

[HondaMan]

A compression check is one way: another (if the head is off) is to turn the head upside down and pour some gas into each chamber to see how long before it runs out - and which way.

[PeWe]

I have heard valve to piston due to chain a tooth off. No problems seen afterwards except small dents in pistons. A light clicking sound.

If you have a compression tester and all are rather equal.
My K2 with stock Cruzing image pistons had 150-160 PSI.  Valves vs seats were recently refurbished.

Cheap compression tester, throttles wide open.
Run on starter, ign off.
All plugs off will help.
Make sure that there are no sand or pebbles on head that can fall inside.

[The Lone Builder]

The engine is still on the bench, but the head is not off. I was thinking to is just to see if all were similar. If so I'd just put it back together. If not, then I'd have to  go further.

Fantastic that you can repair on your tour very far away from home.
A real adventure.

It is fantastic Per, but only possible because of the generosity and hospitality of people who welcome me along the way and the great support and advice I receive from members of this forum.

[HondaMan]

Do you have another head gasket?
And, can you get some Parker O-rings there, part #02-111 ? These are the 2.6x10.8 O-rings needed in those 2 oil ports in the head gasket so it won't leak.
PM me if you decide you need two, I could send those airmail?

[The Lone Builder]

I've made progress!

I removed the head again. On inspection there were marks on both pistons and exhaust valves. I put some petrol into the combustion chambers and after 8-10 minutes, there were no leaks whatsoever, either down the exhaust, or the inlet ports.

So happy days, I seem to have got away with it.

Do you have another head gasket?
And, can you get some Parker O-rings there, part #02-111 ? These are the 2.6x10.8 O-rings needed in those 2 oil ports in the head gasket so it won't leak.
PM me if you decide you need two, I could send those airmail?

I do have another head gasket Mark, thanks, and the o-rings - 2.65 x 10.8. I brought them with me!

So the head is back on and now I'm just waiting overnight so I can re-torque it. Then, with any, unusual, luck, I'll be on the road by Thursday. 🤞

[newday777]

I've made progress!

I removed the head again. On inspection there were marks on both pistons and exhaust valves. I put some petrol into the combustion chambers and after 8-10 minutes, there were no leaks whatsoever, either down the exhaust, or the inlet ports.

So happy days, I seem to have got away with it.

Do you have another head gasket?
And, can you get some Parker O-rings there, part #02-111 ? These are the 2.6x10.8 O-rings needed in those 2 oil ports in the head gasket so it won't leak.
PM me if you decide you need two, I could send those airmail?

I do have another head gasket Mark, thanks, and the o-rings - 2.65 x 10.8. I brought them with me!

So the head is back on and now I'm just waiting overnight so I can re-torque it. Then, with any, unusual, luck, I'll be on the road by Thursday. 🤞

Yahoo! 👍

[MauiK3]

Good to hear!

[bryanj]

Hope it works out

[The Lone Builder]

Uo and running!

https://youtube.com/shorts/dWPQMX5qchE?feature=share

Had a ride of +/- 20Km. Seems to be a bit uneven, but got me home.

Tomorrow a bit of a tune up.

[jaytee-nz]

Great stuff Sean. Sounds like a normal cold CB750 engine to me !

[PeWe]

Nice sound!
I prefer a little bit higher idle to improve start when cold and when riding.
Not that abrupt deceleration at throttle off in low speed and easier take offs.
Minimum 1200 rpm when really warm. 1400rpm is ok too

[HondaMan]

Old Hondas never really die. Some are just allowed to rust away.