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Messages - onethumb

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31
CB750 / Re: Compression numbers.
« on: February 27, 2017, 09:31:02 PM »
Update. Right took the head off and the good news is there is no damage on the top of the pistons and the bores look good. Soaked the top of the pistons with a carb cleaner and wd40 mix for 2hrs and lost none.
Stripped the head but left the valves and springs in placed tipped it over filled the chamber with wd40 and lost it all though the inlet valve in no1 in about 5 seconds, lost most of it out of no4 in about 1 minute though both valves. Now I know I've got issues with no1 and 4 but I think I might get all of them redone.


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32
Project Board / Re: My cb750 scrambler build. Restart
« on: February 27, 2017, 08:25:29 AM »
I noticed blow back through the carbs on number 1 cylinder when hand cranking it over before filling with oil so I could start her up.
Suspect head issues with valves not seating or a bent valve. Trigger gave me the details of someone who can sort it but I need to get the head to him.
On the plus side I'm getting good at stripping her down.


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33
Project Board / My cb750 scrambler build. Restart
« on: February 26, 2017, 11:03:54 PM »
With all the information gained from this forum and the fact that I did it last year I've managed to do this on my own. I do think that every thing is new has made a big difference though.


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34
Project Board / Re: My cb750 scrambler build. Restart
« on: February 26, 2017, 10:54:42 PM »
So I've had a massive issue with the engine so I'm back to where I was back in October. This is a bit disappointing but it needs to be right.


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35
CB750 / Re: Compression numbers.
« on: February 26, 2017, 10:48:33 PM »
Rightio trigger.
I've just ordered a Moore and Wright micrometer and a clutch tool so the checkover can begin.
It has had a rebuild at some time in its life so I don't know if that's a good thing or bad.
What do you think of the numbers?


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36
CB750 / Re: Compression numbers.
« on: February 26, 2017, 09:22:25 PM »
Just did them again with a bit of engine oil in this time. New numbers. After 3 kicks.         After 4 kicks
No 1.                30.                            50
No 2.              150.                          175
No 3.               150.                         175
No 4.                125.                         147

How do these look, do I need to look at doing the rings?

Thanks. Steve.





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37
CB750 / Re: Compression numbers.
« on: February 26, 2017, 07:41:44 PM »
Engine is out now and on the deck ready for stripping tomorrow.


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38
CB750 / Re: Compression numbers.
« on: February 26, 2017, 07:40:28 PM »
I did it with no carbs on and some 3 in 1 oil in the bores.


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39
CB750 / Re: Compression numbers.
« on: February 26, 2017, 04:58:33 PM »
Here's what I got.
No 1.   60psi
No 2.   137
No 3.   148
No 4.   125.
I knew about no1 so that's not an issue. What about the other numbers?
Thanks. Steve



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40
CB750 / Compression numbers.
« on: February 26, 2017, 04:31:13 PM »
About to take the compression numbers and wanted to know what kind of figures are about right. I'll be using the kick start?
Thanks again. Steve


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41
CB750 / Re: Removing head with engine in.
« on: February 20, 2017, 08:39:39 PM »
Hey no worries thanks for the info and the contact.
Not done the test yet I'm away from the bike this week so I'll test it next week on the kick start then I'll remove it from the frame ready to strip.
Anything I should look for that might show up something other than a head issue?


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42
CB750 / Re: Removing head with engine in.
« on: February 20, 2017, 03:16:19 PM »
Trigger thanks for the info. I spoke to Barry this morning,(he knows his onions!) I'll be getting it to him as soon as I've stripped the whole bike down again and removed the head.
Thanks again.
Steve.


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43
CB750 / Re: Removing head with engine in.
« on: February 19, 2017, 09:48:03 AM »
Bryan and trigger I'm one of those people


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44
CB750 / Re: Removing head with engine in.
« on: February 18, 2017, 07:32:36 PM »
Trig, pm sent.


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45
CB750 / Re: Removing head with engine in.
« on: February 18, 2017, 04:35:29 PM »
Hi Bryan. It's the 1978 f2. Doh. Any recommendations for getting new ones pressed in, and do I now do all of them?


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