Topic: Honda 350/4 - close ratio gear box?

[HondaFreak]

All,

In addition to the 500/4 that we are building (nearly done!), we are also having a go with a 350/4. The only major snag we have hit, so far, is that the gearbox is narrow and the ratios are very wide, especially between 4th and 5th.

Does anyone know if a donor box from another honda can be used or, even better, whether anyone ever made a close ratio box for this model - anyone from the USA please contribute, as we know that is where the majority of bikes were sold.

Any help would be appreciated. The frame, a one off, has already been made and the engine is at 'my mates' (Race Developments, Gloucester) for significant porting, valve seat and combustion chamber work. Would be a shame if we are compromised with the g/box

Thanks in advance,

Pete 'Honda Freak' Jones
Part of the Davies MotorSport entourage

[specweld]

I think Gerrit (classic bike tuner) is probably the man to ask............

[classic bike tuner]

i  did som testing fitting with a gearbox from a 250-400N  [6speed]
the gearbox itself fits in between the cases with minor work
need to replace a bearing and the first gear on input is to wide
and schiftforks are to thick
but the problem is to control the gears  [schiftdrum]
a 400 drum perhaps may work but dont fit in the cases
its all a while ago [5 jears ] may forgot samthing

ratio's           
                   1é vers  15-41 = 2,733         
                   2é vers 19-37 = 1,947         
                    3é vers 22-34 = 1,545           
                   4é vers 25-32 = 1,280         
                   5é vers 27-29 = 1,070           
                   6é vers 29-27 = 0,930   
6 speed is slightly longer [3,5%] than the stock 350-5th 

gerrit

wish you merry cristmas and happy new year       

[Howell]

Don't tell them to much Gerrit , it's business for them

[Howell]

Pete , How about the development of the 500 engine ?

[bwaller]

The similarites between 350 & 400F models would surely make one think that would be the closest 6spd option. I have a 400F engine open here but it's been too long for me to remember if the 350F shifting mechanism is similar? Both use three forks on a separate shaft.

As cbtuner seems to have tried I expect if it was easy he would have proceeded. I fit a CB360 6 spd into a CB550 and the biggest hurdle was the shift drum, however with much modification it works well. I looked at newer model boxes first and the shift drum/forks is always the issue.

I'm sure you know a couple of your countrymen who can help. Ellis Moore (Moore Performance Engineering) made some gears and a mainshaft for me to tighten the 360 ratios. Thinking you could improve the stock 350F gearbox by having a taller first gear and tightening some of the rest, although that will be a complete re-do.    You might also contact forum member Kevin (TTR400) who has done work on the 400F gearbox. He might have looked into the 350F also??

Good luck, and please know we're awaiting news on the 500 development. 

Opps, looks like Rene is ahead of me!

[HondaFreak]

After much deliberation, JD has decided to commission a new close ratio, 5-speed box through Nova to suit the 350/4. It seemed the best way to actually get what we wanted without compromising the ratios and ensure a solid gear change, with proper square cut dog teeth on the gears.

With regard to the 500 engine, we are still waiting on some shell bearings as the engine builder wasn't happy with the ones we had. They should be with us by end of this week. I think that is the last hurdle then and he can crack on. The lightened primary gear from Nova is on stock, the CRs are here and we have exhausts to run with (but untuned). Its got to be done by the end of Jan or we will be up said creek without said paddle. It has been a frustrating wait.

Couple of minor bits to sort out like ignition pick ups once its done, other than that we should be able to proceed to the dyno.....

350/4 engine development also kicks off from Saturday....that is possibly more of a challenge

Pete 'Ever Hopeful' Jones

[classic bike tuner]

got it reddy 

[bwaller]

Hi Gerrit, is that a modified 400F shift drum?

[classic bike tuner]

drum is new custom made
 special for the 350 cases and use with the 250N/400N gearbox

[johno]

 Nova racing have a big range of different model Honda close ratio gearboxes on their books, They custom make any gears if you want an odd ball ratio ( like me with 1:1 fourth, no fifth) the cost is approx 400 english pounds for the pair ( need two matching gears)  and if different from their close ratio's  have to send them a stock gear so they get the odd ball gear right.          pity the exchange rate for ozzy dollars to pounds is crap.
They are on the ball service wise..............my goodness sounds like an add
johno

[classic bike tuner]

if you can get the gearbox a bit scheap [ebay ] and the selector mechanism/forks you can get the six speed for 300 euro working  maeby even less
look for a good one with no pitting

drum only  mail me c.b.t@outlook.com
gerrit

[classic bike tuner]

   guy hildred askt me for a drum

but cant reply on his mail 

guy.hildreth@bogpond.com

[classic bike tuner]

Uw bericht kan niet worden bezorgd bij de volgende geadresseerden of groepen:

your message can not be delivered

guy.hildreth@bogpond.com (guy.hildreth@bogpond.com)

[Retro Rocket]

Uw bericht kan niet worden bezorgd bij de volgende geadresseerden of groepen:

your message can not be delivered

guy.hildreth@bogpond.com (guy.hildreth@bogpond.com)

That email address is wrong, it should be bigpond, not bogpond, I don't know the guy you are trying to contact but try this, watch the spelling    He is an Aussie yes..?

this email address should work

guy.hildreth@bigpond.com

 

[classic bike tuner]

alreddy try dad

and    it workt  got a reply

but how is that possible 

[xjrguy]

Hi, guys!
I am the newbie on the block!
I am starting to pull together the bits to build a 350F racing bike after spending time as pit-crew for Neil May who races a replica manx Norton and a Honda CB350 twin here in Oz.
I live near Melbourne (a place called Riddells Creek), so am close to Phillip Island and Broadford race tracks (Riddells Creek is about 20 minutes north of the Melbourne airport)
I have been over the IOM a few times and struck up a conversation with John Davies who builds 350F racers. He also built Neil's bike.
I have now built a race frame from him, a set of his racing front forks, triple clamp set and ignition system.
The idea is that I will build the engine myself (retired mechanical engineer) over the next couple of years and get Neil to race it.
I have made contact with Gerrit and he has been amazing in supplying me info on how to do the 6-speed conversion on the 350F.
Nothing much will happen for the next year as my wife and I are travelling in Europe, but as soon as we get back, I hope to get into it.
Any advice on how to build a nice strong engine would be greatly appreciated.
I have myself a set of Carrillo rods (ouch!) and want to do this right.
Hope to see some of you at the racetrack.
Regards
Guy Hildreth

[bwaller]

Your Carrillo's are a great start! If your ignition system doesn't include a rev limiter, add a separate unit. Adequate (but tight) clearances help keep it together as it'll like to rev.

Sounds like a fun project.

[bear]

Welcome to the forum Guy.
Look forward to seeing you around the traps.

Cheers,
Brian

[xjrguy]

I would appreciate any advice you guys can throw my way about what I should be doing inside the engine to;
a) stop it exploding   
b) get the most out of it   

The head is the area where I know the most improvement comes from.
I will port and polish everything and use a good cam, but I am show that there are plenty of tips and tricks out there that I can use!
Can anyone tell me what areas I should be concentrating on;
- modifying valve size?
- type of cam that works
Cheers,
Guy