Possibly entering the 378 club!

dynamic timing just take the alt cover off - if the bike is on the center stand it won't leak much.

as for springs, all suppliers I know have them are U.S. based
 
Basically with the timing light you want the hash mark to line up smack in the middle of the two advance marks when the motor is running @ full advance which is about 4k rpm.
 
Thanks both

Ive found a local supplier of EBC hd springs, will give those a try.

I have an adjustable timing light, can set desired advance degrees and the flash should line up with tdc mark.

What is the timing supposed to be at max advance, eg 30 degrees before tdc ??

Steve
 
manual says advance angle is 0-12.5 with advance starting at ~1800rpm and full advance occurring at ~3400rpm
I guess that means full advance is 12.5* -
 
Cam runs 1/2 crank speed so 12.5 would be 25 crank angle. Pretty sure I've measured it nearer 35 degrees though so maybe 123.5 is 'F' mark? (It's a long time since I read manual ;D )
 
I’m still awaiting delivery of the hd clutch springs and some zener diodes to ‘finish’ the build but the cb390 is running great.

I’ve had a couple of blasts on bigger roads now and feel confident of joining the Ton Up Club real soon !

Thanks for all the help and advice guys, i wouldn’t have attenpted this without the DTT forum and your inspiration !
 

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Thanks Cursh, i am pleased with how it turned out.

I started searching for ‘390’ badges and there are a few Ford ones.
Then it dawned on me, ‘badge engineering.
It’s almost as rewarding as ‘cardboard aided design’ :)

Steve
 
crazypj said:
Cam runs 1/2 crank speed so 12.5 would be 25 crank angle. Pretty sure I've measured it nearer 35 degrees though so maybe 123.5 is 'F' mark? (It's a long time since I read manual ;D )

Total advance at 4000revs will be static advance plus 2*dynamic/cam advance.

Static could easily be 10 hence 35 total is about right.

I’ll have a test and report back, will be a few days though with work and it being too hot here in London at the moment !

Steve
 
Oh, and here’s the Tacho on a temporary bracket next to the ‘Ton Up’ speedo.

Speedo is the original with a beautiful new face made by Matt/Sonreir :)

Steve
 

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advCo said:
Awesome. I like the blue backlighting, but does it effect your night vision when night riding?

The speedo doesnt but have yet to try the tacho at night.
Am having trouble getting the tacho to work so ot may not be there long!
 
Sderbyshire said:
The speedo doesnt but have yet to try the tacho at night.
Am having trouble getting the tacho to work so ot may not be there long!

I have never had good luck with those electronic tachs that read the pulses on the HT wire. On my XL I plugged the Trailtech tach lead directly into the connector that led from the points to the coil. It was better functioning than I've seen from wrapping around the plug wire lead, but still jumpy and fairly inaccurate.
 
Went for a spin around the country lanes this morning, CB390 running great!

I have a few issues to work on, but 90% there.

Issues are :

Bit of ‘popping’ from right exhaust on overrun and tickover, i’m thinking its an air leak in the exhaust?
Tacho not working, awaiting opto-isolators
Clutch slipping a little, have new springs to fit
Neutral difficult/impossible to get when hot, was like this before
Oil change after rebuild, wondering whether to use fully synthetic or semi?, 10w40.

Steve
 
Whatever oil you use, make sure it meets the requirements of JASO-MA. Personally I use Rotella T4 15w-40 for all of my wet clutch bikes, but the oil debates are far and wide.
 
irk miller said:
Whatever oil you use, make sure it meets the requirements of JASO-MA. Personally I use Rotella T4 15w-40 for all of my wet clutch bikes, but the oil debates are far and wide.

Thanks, do you use ma1 or ma2 spec oils?
I dont see the rotella much on this side of the pond, usually use Shell Ultra 4t in the Ducati’s which is MA2 spec, but they are dry clutch?

Is fully synthetic appropriate for these old Honda’s ?

Steve
 
Pretty sure MA2 is an added distinction for bikes with catalytic converters, so either should do. I use the dino oils, but I think synthetic or conventional is good. In a climate like Georgia, I don't see much need to pay the extra cash for the synthetics.
 
Sderbyshire said:
Thanks, do you use ma1 or ma2 spec oils?
I dont see the rotella much on this side of the pond, usually use Shell Ultra 4t in the Ducati’s which is MA2 spec, but they are dry clutch?

Is fully synthetic appropriate for these old Honda’s ?

Steve
I run full synthetic in mine but it's Rotella again (5W/40 plus 2oz ZDDP per 5 litres) Pretty sure you can get in touch with Shell (they have a forum for bikes) and find out what it's called in Britain/Euriope. Mobile 1 is also OK for wet clutch (according to Mobile spec shets) Brendon is also using Rotella 5W/40. When I stripped his bike, cam and rockers were in better condition after 2,500 miles than when I originally built it (more 'polished') His cam is also 'gun drilled with drilling's for each bearing and lobe.
 
crazypj said:
I run full synthetic in mine but it's Rotella again (5W/40 plus 2oz ZDDP per 5 litres) Pretty sure you can get in touch with Shell (they have a forum for bikes) and find out what it's called in Britain/Euriope. Mobile 1 is also OK for wet clutch (according to Mobile spec shets) Brendon is also using Rotella 5W/40. When I stripped his bike, cam and rockers were in better condition after 2,500 miles than when I originally built it (more 'polished') His cam is also 'gun drilled with drilling's for each bearing and lobe.

Thanks PJ

I thought zddp was more for flat tappet engines, i have a 1974 TR6 car and we are forever debating which is the best oil for those engines. Mine is tuned to about 180bhp and i favour Valvoline VR1 which is both hin in zddp and comes out near the top in film strength tests.

Wasnt expecting zddp to be an issue on the Honda!

My default choice is Shell Ultra 4T, which is probably overkill but i can then share it with the Ducatis.

Steve
 
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