Possibly entering the 378 club!

It may not be needed but as I know 250/360 has top end issues I decided tro be safe rather than sorry. The rockers are similar to a flat tappet as they have to slide over cam, but, unlike flat tappets, they don't rotate. (I had an old Rover and a Chevette I was going to 2.3 rally spec,etc but sold it and put motor in Manta GTE 8) Never had Manta over 125MPH but that was 'uphill' late for work one morning
 
crazypj said:
It may not be needed but as I know 250/360 has top end issues I decided tro be safe rather than sorry. The rockers are similar to a flat tappet as they have to slide over cam, but, unlike flat tappets, they don't rotate. (I had an old Rover and a Chevette I was going to 2.3 rally spec,etc but sold it and put motor in Manta GTE 8) Never had Manta over 125MPH but that was 'uphill' late for work one morning

Opel Manta GTE, that takes me back, white i presume
 
Bike is running great, apart from one carburation issue.

There’s a hesitation and occasional stall when opening the throttle.

At the weekend i reset the timing and adjusted the idle mixture screws to get a strong idle, bike seemed to be running better than ever.

Out for a test ride and there;s a hesitation on opening the throttle, and occasionally it stalls. This is when i open the trottle to pul away, seems to be worse the faster i open the throttle.

Have i made the mixture too rich do you think?

I am running foam pod filters but havent had this problem before, they’ve been on for a year.

Suggestions please!

Steve
 
Nope, Black ;D The problem with carbs is 'normal'. Around 4,000rpm slide starts lifting and adds too much fuel. If you fit a smaller secondary main jet to 'fix' that problem, you end up very lean around 7,000. If it was possible to fit a needle with longer parallel section it should fix things. It may be easier to find CB160 needles in Britain, I've heard they work but don't have any experience with them
 
crazypj said:
Nope, Black ;D The problem with carbs is 'normal'. Around 4,000rpm slide starts lifting and adds too much fuel. If you fit a smaller secondary main jet to 'fix' that problem, you end up very lean around 7,000. If it was possible to fit a needle with longer parallel section it should fix things. It may be easier to find CB160 needles in Britain, I've heard they work but don't have any experience with them
Ok so is it normal for misfire while cruising at that rpm? Should I cruise at a lower/higher rpm?
 
MiniatureNinja said:
Ok so is it normal for misfire while cruising at that rpm? Should I cruise at a lower/higher rpm?
It's not normal. It needs to be tuned out. Maybe it's common for 360s, but it sucks and I wouldn't call it normal.
 
Sderbyshire said:
Bike is running great, apart from one carburation issue.

There’s a hesitation and occasional stall when opening the throttle.

At the weekend i reset the timing and adjusted the idle mixture screws to get a strong idle, bike seemed to be running better than ever.

Out for a test ride and there;s a hesitation on opening the throttle, and occasionally it stalls. This is when i open the trottle to pul away, seems to be worse the faster i open the throttle.

Have i made the mixture too rich do you think?

I am running foam pod filters but havent had this problem before, they’ve been on for a year.

Suggestions please!

Steve

Could possibly be a vacuum leak. Right before I sold my 360 it developed a tiny leak where the intake manifold meets the head. Bike idled great but as soon as you cracked the throttle it wanted to stall out. I was able to get an RPM surge by spraying some ether around the intakes but had to find the EXACT spot, so it was a tiny little vacuum leak. Cut some new gaskets and sealed both sides with Yamabond and off we went.
 
advCo said:
Could possibly be a vacuum leak. Right before I sold my 360 it developed a tiny leak where the intake manifold meets the head. Bike idled great but as soon as you cracked the throttle it wanted to stall out. I was able to get an RPM surge by spraying some ether around the intakes but had to find the EXACT spot, so it was a tiny little vacuum leak. Cut some new gaskets and sealed both sides with Yamabond and off we went.

Interesting, i’ll investigate, thanks.
 
You can also try advancing the ignition timing a couple of degrees and see if that helps. Don't exceed the maximum advance, though.
 
irk miller said:
It's not normal. It needs to be tuned out. Maybe it's common for 360s, but it sucks and I wouldn't call it normal.
I should have been more specific. It's 'normal' for unmodified carbs. As SD is in England it isn't practical for him to mail them to me for modification but, Dave Silver may have CB160 needles cheap enough to experiment with. A stock 360 needle would be too long if slide is modified to drop it 1mm.(equivalent of going down two notches on adjustable needle)
 
Sderbyshire said:
70mm pistons arrived from Japan in less than a week!

Off to the machine shop today
Do you have a source on these pistons? I used the google machine without success.
 
Yes, i found a seller on ebay and he was very helpful

Email is info@cruzinimage.net contact name Mitsuo

They arrived in a week from Japn to London, no problems with them at all.

Steve
 
erock85 said:
Do you have a source on these pistons? I used the google machine without success.

This is also an option...
 

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Sderbyshire said:
Yes, i found a seller on ebay and he was very helpful

Email is info@cruzinimage.net contact name Mitsuo

They arrived in a week from Japn to London, no problems with them at all.

Steve
Awesome, thank you so much!

Sonreir said:
This is also an option...

Great! I love options
 
What an awesome log. I'm now convinced to jump on the 390 conversion.

Next I'll go through MiniatureNinja's project log.
 
Recently I took some measurements of GS850 and CB360 liners. The CB are actually thicker than the GS so it should be possible to go to 71mm without boring block and fitting new liners.
I don't think it's worth fitting larger liners to go to 72mm though, it's just as easy when boring blocks to go to max size. If step-grandson ever gives me time I'm going to finish off the 75mm block I started working on years ago (using Suzuki GS500 liners)
 
Just installed mine from the same eBay seller. PJ helped me on the carbs. Can’t wait to ride!
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