What performance parts are WORKING in your CB350??

[Bobdot]

Hey all,

Been reading through the interwebs about all sorts of performance upgrades for the CB350, of which there are many (providing you have the coin).  I've been making notes on the mods that are more cost efficient and will try to keep this first post updated with links to information as it comes in.

If you got any other performance suggestions, feel free to share.

Todd Henning Racing - High Performance Racing Parts for full-bore racers
http://web.me.com/thracing/THR/CB350_K4.html

Team Hansen Honda - High Performance Racing Parts - No idea how much anything costs yet (350 Parts towards the bottom of the page)
http://teamhansenhonda.com/parts.htm

Bore-Tech - Performance parts for racing and street
http://www.bore-tech.com/CB.html

Dennis Kirk - Good site for random parts (Gaskets, sprockets, brakes, etc), also has good levers and a High Output Stator (Single Phase, full wave)
http://www.denniskirk.com/jsp/tpl/cmn/prodlist.jsp;jsessionid=JZDATSF5XAFAXQFIDYESM4WAVAPAQIV0?store=Main&category=4&mmyId=1844&page=1

Motobits - Rearsets specifically designed for the CB350
http://www.motobits.com/vintage.html#CB350

Jerry's Cycles - MAC 2-1 exhaust pipes (sold out at the moment Oct '10)
http://www.jerryscycles.com/catalog/i19.html

Blogs/ Journals on CB350 Performance Tuning and Building

How To Build a Honda CB350 Vintage Road Racer by Eric Kalamaja
http://www.motorcycleshopper.com/articles/hondacb350/foreword.htm

VINTAGE-ROADRACE LIST CB/CL 350 RACE BIKE FAQ by Chris Marshall, Hoyt McKagen, Chris Ford, Buff Harsh, and Seg Niebuhr
http://eurospares.com/350faq.htm

Nisky Garage by Rick Ketcham and Rich DeSimony
http://niskygarage.logical.net/CB350/index.html

Posts from other Forums that can be useful

"Race Prepped CB350" on .net - takes a while to weed through the bullshit but there's good stuff in there and an amazing build
http://www.caferacer.net/forum/topic.asp?TOPIC_ID=11530&whichpage=18

"CB350 - a little more power" on avdrider - good technical stuff, lots on jetting
http://www.advrider.com/forums/showthread.php?t=598092&page=3


bob.

[TonyD]

i'm running 750 pistons in my 500..........................

[joevirus563]

i'm running 750 pistons in my 500..........................

Please explain your setup

[Cat13]

I've got a 360 and if I can bore it out for a larger size piston please let me know! A cb750 would be tits if I can do it...

[teazer]

CB750 has a 61mm bore IIRC and the CB350 is 64mm. CB750 has a very low piston crown so that would drop compression if you sleeved it to fit.

Now if we look at 12.5:1 CR 65mm (836 kit) pistons, that might be a possibility.  Valve pockets are all wrong on a SOHC 4, but they might be possible.  We have a Wiseco 64mm KZ piston and a CB750 WISECO and stock CB570 and CB350 and 360 pistons that we have bought to look for alternatives and so far no luck.  I'd like to see a super high CR 836 kit piston to see if that might work.

A better answer is to contact Les Barker and get a pair of these http://www.vintageadvantagemotorcycles.com/vintage%20advantage%20website%20photos%20350.jpg

[crazypj]

You got it backwards, you fit CB350 pistons to a CB750 for a cheap 836 kit

[Bobdot]

this is what I'm talking about, lets get down to the nitty gritty.  What WORKS, and what doesn't.  I demand not only answers, but explanations!

bob.

[Bobdot]

Dare I bring up type 1 cams?  Higher revs I hear?

bob.

[crazypj]

Are you working on a 350 or a 750?
 CB750 pistons fit into CB125 to give a 145cc motor (need mods to get clearance)

[Bobdot]

I am working on a 350, looking for options.

[Rocan]

I am working on a 350, looking for options.

bore-tech pistons are your best bet on a street motor. 1.5mm oversize, plus you can run a big cam if you wanted too. if you want a cheap route; try and locate some GT750 pistons and throw those in... bump up compression a bit as well as are oversize, but dont have cutouts for a big cam.

As for k1 cam; they are, apparently, more prone to failure (thats why they were changed in later years), but yes, it is agreed that they perform better. higher revs, slightly higher lift. not going to be "lumpy" but a nice addition, if you find one in good condition and cant afford a megacycle. YOU NEED THE MATCHING ROCKERS!

also, SEARCH. most all of this has been covered here, or on another site such as caferacer.net, hondatwins, etc. google is your friend.

[Bobdot]

Oh, I've been searching for the past 3 years.  Thats the point of this thread really, I've read hundreds of "suggestions" and very very few actual testimonials from people actually running these parts in their running engines.

I dont mean to call you out Rocan, but how do you like the GT750 pistons performance compared to your Bore-techs?  How is the power through the revs on that megacycle? I'm not trying to be a dick, I'm just looking for cold hard evidence to back  all of the here-say info I've been bookmarking on my computer all these years.  With all the extensive info floatng around, I'm attempting to cut through the crap in order to save time and money, both of which I am limited on.

bob.

[teazer]

Bob,
PJ and I explained the CB350/750 thing from different ends but hopefully that myth is blown back to where it was germinated.

Type 1 or Megacycle cams.  Bore-Tech or THR or Vintage Advantage or other pistons etc begs a question - what is you intended outcome? Are you looking for a full house race bike or a mild street bike with a bit more get up[ and go?  A bike that's smooth from the bottom end or has a powerband like a 2 stroke?

Within those objectives you will get various opinions and the success or lack of it may be more related to the person doing the work that the parts. For example if I recommend a certain cam and slip it in and PJ suggests another, but PJ takes the time to dial in cam timing to where he wants it, which combo will be better?  Rhetorical question of course.

The generic answer is add more capacity - you can't beat cubes. Add more compression for more bottom end punch.  Add a cam to add more further up the powerband and more compression to try to bring back some of the bottom end.  Add better gas flowed ports to match the carbs and RPM/HP limits you are working to.

In the end it's all suck it and see and then the D part of R&D comes into play. Adjusting cam and ignition timing etc to develop what you have. We like to do the analysis and start with two perspectives. !- what do we have - measure the port shapes or take rubber molds of the ports to identify what we are working with and getting the gas flow numbers from the stock head helps us to understand what we're dealing with.  Then set an objective and work out how much gas flow we need to meet that objective. 

Some heads flow well at low valve lift but poorly at higher lifts and they respond differently to different cams. match the cam to the flow patterns and balance all the port dimensions from carb to valve and get the most out of it.

But for a street bike, set a budget and an objective and look at your options.

[djelliott]

Hey Bob. I've got a few for you. Here's a list of what I've done to my Cb350 motor. Mind you. I can't exactly tell you what each and every individual piece has contributed because I built the motor all at once. I can tell you it runs beautifully though.

Motor:
NOS Rocky S12 (3.0mm) overbore pistons. Brings the displacement up to about 358cc from 325cc or roughly that of a CB360. In fact I couldn't find S12 rings so I took a chance on the 360 rings and they worked perfectly. Sure would be nice to have that 6th gear though.

Later model SL350 Cam. heard about this from some old school Honda fellows. They said it was a cheap mod back in the day to get more low end torque. The SL cam has a slightly different intake duration. Upon inspection and comparison I found this out to be true. I apologize for not writing down the numbers. I also did some mild porting to the head. Really just a clean up and a bit of smoothing out.

Tsubaki Cam chain and KA Performance cam chain slipper. had to replace them anyway so I bought into the word that this was the set up to get. Only time will tell I suppose.

Also running Mikuni VM30's and a Hondaman transistorized ignition. The Hondaman is cool. Way big difference in spark quality.

How does it all sum up? Well, after awhile of tuning the carbs and tuning the carbs and tuning the carbs while breaking the motor in, it rips off the line like a bat out of hell. Lots of pull and I'm happy with the power all the way through the band. Still really has the top end of a 350. I don't think there's much to change that especially with the SL cam and the fact that I have scrambler sprockets. I have no problem holding 70+ on the highway and have even passed up into the 80's. Haven't been doing that so much because the motor really is still young.

I hope any of this helps. I wish I could give you different data on each but I only know the sum of the build. Having ridden MANY CB350's I can tell you for sure I have a different animal. Someday I'd like to get it on a dyno for some concrete numbers. BTW, most of these mods cost me very little money compared to the racing prepackaged performance stuff. A little patience and frequent eBay visits can turn up some cool shit for not much.

[Bobdot]

DJ - Thanks for that info, thats the kind of info I'm interested in, I'm taking notes.

Teazer - Also very helpfull, I have some descisions to make regarding what I want in the end.  Thanks for explaining the cause and effects very clearly.  Although I've been toying around getting involved in some vintage racing, I simply dont have the extra cash to invest in that sort of comitment right now.  I guess I'm looking for a street legal corner burner.  How I have it tuned right now, I'm happy with the low end (unless im going up a hill) but I'm left wanting more on the straights.  I can get to 70mph quickly and then it turns into a bit of a dog.  Don't get me wrong, it runs strong but I know they have a lot of potential to unlock.  I've got some maintenance work to do to the engine this winter so if I'm going to open her up again, I myaswell spruce it up a bit.

I've got some studying to do in regards to cam timing and port matching.

Thanks and keep it coming, its all helpfull.

bob.