Author Topic: CB350 Racer  (Read 7041 times)

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Offline Tintop

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Re: CB350 Racer
« Reply #25 on: December 01, 2016, 03:59:11 pm »
+1 TG
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1976 CB400 SS - stock / BOTM 04/11 (SOLD)
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77 CB550 Cafe build
550/750 Filter Thread
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Offline scottly

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Re: CB350 Racer
« Reply #26 on: December 01, 2016, 04:21:37 pm »
The CT 70 (Dax) had a 47mm bore, as well as the newer XR70R and CRF70F. It appears the 400 has a 26mm intake valve, and a 23mm exhaust, and the edges of the valves would be very close to a 47mm cylinder bore. Does anyone know the 350 valve size?
It seems odd that a 400 could be competitive in a 500 class, but not a 350 in the 350 class??
Also, how much does it cost to make 45 HP with the twin, vs 30 HP with the four?
 
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Offline ttr400

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Re: CB350 Racer
« Reply #27 on: December 01, 2016, 09:11:27 pm »
The 400F inlet valve is 26.5mm exh 23.0mm
The 350F Inlet is 26.0mm and Exhaust is 22.0mm.

In the past i have managed around 58-60 RWHP from a big bore full house 400F engine. best i have got from the 350F with a 400 bottom end and 1.0mm over std Honda pistons was 44 RWHP. this was also a full house engine. this was revving to around 13000 rpm.

These little engines need to breathe and lots of revs (:

Kevin
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Offline turboguzzi

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Re: CB350 Racer
« Reply #28 on: December 02, 2016, 07:40:21 am »
hi ttr, good to see you here... your disc carriers are still giving good service :).
the hp numbers above are for stock displacement? if yes, then 44hp is better than i thought, but guess we are talking carillo rods, OS valves, 13:1 pistons, etc ?
Scottly, not odd, a punched out 400F  to 500 is a light "500" with almost 500 power, a 350F-350F is a 350 4-cyl that's not exactly light and not with not stellar power for a 350... :)

« Last Edit: December 02, 2016, 02:14:52 pm by turboguzzi »

Offline 754

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Re: CB350 Racer
« Reply #29 on: December 02, 2016, 08:55:25 pm »
Kevin tell us more about the built 350-4... Cant be a huge choice of cams and stuff for them...
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Offline scottly

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Re: CB350 Racer
« Reply #30 on: December 02, 2016, 09:15:26 pm »
Hey Kevin, thanks for your input. I would also like to hear more specifics on both the 350 and the 400(+). ;)
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Offline kubricky

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Re: CB350 Racer
« Reply #31 on: December 03, 2016, 06:49:26 am »
BLUF: Is there a fiche type site for vintage bikes with the detail/resolution to identify parts?  Are used OEM parts for these bikes (mainly gas tank, exhaust, misc brackets, airboxes, light, gauges, etc.) all that sought after?  Is it worth my cleaning these things up and posting for sale to offset the costs (I know I won't get much, basically some of the key items that I got with the bike are for a different model).

Okay, folks I can't thank you enough for the responses - and I am sorry for the radio silence.  I commute about 200 miles a day for my work and while it is my choice, I am starting to question the value of working for the fed.

More importantly I am sorry for taking a picture like that and posting it so it is so tough damn tough to view.

With the motor in, I had hope that I might get this thing together for a trip to Jennings in in mid February.  Unfortunately, I have to be realistic and realize that it'll probably be closer to May before I can get it to a trackday for a test and then get to a few local WERA events to flush it out in a race scenario.

First things first, I'm ordered the Dyna ignition, I know that there are a lot of options, but that seems the most reliable.  The plan is to have the motor running (if it will run) over the next two weekends.  That seems like a critical path item so I want to see if the motor is solid.  I've also found that a few key parts that came with the bike appear to be CB550/750 parts.  For example the pipes and tank appear to be from another model.  The pipes because they are marked CB550 and the tank because the petcock and mounting tabs do not appear to be the CB350 stock based on parts available from places like DimeCity, David Silver, and Common-Motor.  Not sure if you guys use these three places but they seem solid to me.

I can make the two sets of pipes work for the initial firing but I'll likely pick up a set of the Mac 4 into 1.  How likely is it that I can sell the pipes and tank to use to offset the cost of replacements?  For instance is there a wiki type reference site where I can take a good look at the tank mounting latch (where the rubber mounts) to see if there is really a difference between what I have and what I need - maybe I received the wrong rubber mount)?  I am using the type of petcock as the initial indicator that i have the wrong tank.  That all said, the tank I have is in pretty good shape, I've cleaned it up and I'd use it if the suggestion is that year/model doesn't really matter.  Bottom line, for me, on a race bike, I'll put a bolt through the tank tab so the mounting rubber is sort of a moot point.  As mentioned earlier I'm struggling with this almost romance with these old machines and I feel bad about cutting, modifying, and taking away from the original.  I've got buddies that are getting me out of that though.

Based on the advice above I am going to do flat stock braces with a tube braced through to hold a simple bracket for rear-sets in place of the saddles - while I like to kid myself, I don't have a machine shop and have to make do with the basics.   This isn't critical path yet though so I just wanted to let you guys know that i am paying attention to the advice.

Offline calj737

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Re: CB350 Racer
« Reply #32 on: December 03, 2016, 09:58:27 am »
May I ask, where about are you? Gotta figure either MD or VA?
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Offline kubricky

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Re: CB350 Racer
« Reply #33 on: December 04, 2016, 09:08:23 am »
yes sir, Md. I'm going to hit that Appalachian Motorcycle "swap" in January at Howard County fairgrounds.  Apparently it is pretty good but when I think back to the late 70's and early 80's and "ham fests" I've seen nothing like it in 30 years, but with the chain stores and then the internet took that business over and must be the same thing for motorcycles.

I'm not going to waste everyone's time with a picture until next weekend - I'll have the ass-end of the bike close to finished (mock-up) with the tail from airtech, the cheap chinese shocks (I know, I know, but I wanted to give them a try, they are adjustable and I wanted something I could really work with like the ohlins), and little things like the stiffeners and my custom and not very trick at all rear stand clips.

Thanks again for all the responses.