Honda Cb350 Flat tracker

simon walsh

Member
Dec 13, 2020
19
10
What's inside the motors ?

Before I found the mint CL, I had a pair of 350 projects.

There's been a lot of work invested to clean everything and repaint the motor castings as Honda originally supplied.

I purchased quite a few performance parts. One cam is Megacycle's 13,000 RPM item with the housings converted to needle bearings.

The #1 project was an SL-K2. I was debating the direction to take. After buying the CL, I took a break.

Later, I found a NOS K2 cam and decided to build that motor as original. It's close to being finished.

Project #2 is a late CL which will be assembled with the hot-rod components. I didn't like the spring kit and need to buy something different.

Kibblewhite parts should do the trick.

The CL chassis will be pretty standard. It should make for a healthy-running, early 1970s style off-road scrambler. Cosmetics & paint are original.

The SL-K2 chassis has new paint, Franks' fork tubes, Koni shocks per originals, and appropriate details. Call that one a super stocker and fully equipped. Replica exhausts will be needed and they are a bit pricey when available. The tank could use a fresh coat of " Panther Gold " paint.

 

simon walsh

Member
Dec 13, 2020
19
10
Hi Mate,
Yes for some reason my reply didnt appear - my race engines have flowed heads , lighter stainless steel valves, Kibblewhite race valve springs , race cam , taken out to 346 cc (66mm) , Arrow rods ,Omega pistons ,Cam chain slipper conversion , standard crank , uprated clutch , close ratio gearbox , Mikuni 32mm VMs, Programmable Ignition (total loss)
Regarding the 13000 rpm Megacycle Cam you mention (X5?) - in my experience if you rev a CB350 to 13000 rpm many times they explode... I get peak bhp at 11250 rpm.
The flat tracker engine is standard apart from being a 346cc also , Mikuni 30mm VMs and same ignition as my road race bike
Regards
Simon
 

AHRMA92

Active member
Dec 9, 2020
41
28
Here's one that good for this webpage. A George Garvis built Honda SL350 rigid. This bike was sold @ the Mecum MC auction in Jan 2017. Pretty sure the hammer price was $5500.00 plus the Mecum percentage & Clark County (Las Vegas) sales tax.
 

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AHRMA92

Active member
Dec 9, 2020
41
28
Nice looking racer & unique battery box placement for the total loss system on the #1N Honda. Though not a Honda, my Sonicweld BSA has it's location behind the front number plate,
 

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ambike

Active member
Dec 10, 2020
47
44
Simon : Those are good specs. re 13,000 RPM - You have it right. @ 13 k a mean piston speed of 4300 ft./ min. is getting there . Revving thru the low gears to max RPM would take its toll. Downshifting a wide ratio gear set would be worse. Pulling a high gear with a steady load would be feasible when needed.

Over all those years, what components have given you trouble and failed ?

Are you running a dry clutch ? What about the oil pump and brand of lube ?
 

simon walsh

Member
Dec 13, 2020
19
10
Hi,
Probably the component that has failed most is big ends - but in all those years i have managed to break most things............
Standard clutch but with CB500/4 friction plates and springs - CB 350 steels (cant use dry clutches in our series)
With regard to the oil pump - again standard but i always pay particular attention to primeing the top end (small 6 mm bolt removed on Cam box as well as plugs and spun over on paddock rollers until oil appears at hole). After a rebuild or if the engine has been stood for a while the small ball bearing in the pump can stick and thus not allow oil through to the top end - equals trashed cam and rockers
Regards
Simon
 

oupa

Active member
Dec 20, 2020
50
35
You guys are killing me! I have an SL350 race bike project sitting in my shed right where I stopped one day two years ago when I got sick. Close enough to "done" to look like a motorcycle again, but still a long way from running/riding.

I'm all better now... physically at least, my wife would debate that diagnosis regarding my mental health. ;) I've finished most other projects I have been able to undertake since then (with one BIG exception) and now, I'm getting the bug again looking at these beautiful Hondas. A long-time (62 years) local Honda dealer recently retired and finishing the bike may be a fitting tribute to her and her late husband who are/were devoted dirt track supporters. Hmmmm. :unsure:
 
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