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Questions - early doors
dern - 10/10/04 at 08:56 PM

Evening,

I'm about to start building my locost and am trying to make up my mind about which engine and so on and wondered if anyone could offer any advice...

I've been driven in a zetec westy and a blade fury so I know a bike engine is what I want, I just don't know which one.

I'd like FI but can fit it to a carb'd engine if need be. I'd like a blade engine as I have a blade and have had it for 3.5 years from new and it's been rock solid. If I go for an FI blade engine do I need a dry sump or can I get away with a shallow baffled sump? Is the late R1 engine better or more or less the same? Does anyone have any other recommendations for an engine? I have a budget of about 1k I guess but would obviously prefer to spend less.

The BEC I was in today was very very nice but the gear changes were very clunky. This doesn't happen on my bike and my guess is that this is because the bike has a cush drive and the car did not. Is there a similar device available for a BEC that soaks up some of the shock on a gear change as there is on a bike?

Thanks,

Mark

PS. Another quick question... I want a LSD to go in this project, do any of the sierra LSDs have a suitable ratio for a BEC?

[Edited on 10/10/04 by dern]

locoboy - 11/10/04 at 10:23 AM

to answer the ones i can............. not all of them!

The clunky gear change is a characteristic of a BEC as far as i know, no one i know has bothered with a cushdrive of any sort.

As for LSD, its a case of is the engine suited to the LSD or is the LSD suited to the engine, some bike engines are better suited to your most common LSD's (3.62) fireblade, R1, ZX9 will all go well with a 3.62 other nike engines have differing output ratios.

Do a search fo gear ratio calcuator on here and have a play about with diff ratios and different bike engines.

all the best

kingr - 11/10/04 at 11:48 AM

I have a cush drive of a sort - torque resilient tube in the rear section of the prop, can't say whether it makes a difference, but other than 1-2 all the changes are fairly painless.

Kingr

dern - 11/10/04 at 11:53 AM

quote:
Originally posted by kingr
I have a cush drive of a sort - torque resilient tube in the rear section of the prop, can't say whether it makes a difference, but other than 1-2 all the changes are fairly painless.
The gearchange on my fireblade from 1st to 2nd is pretty clunky and it has been on every bike I've had so that sounds pretty good.

Regards,

Mark

[Edited on 11/10/04 by dern]

dern - 11/10/04 at 11:57 AM

quote:
Originally posted by colmaccoll
to answer the ones i can............. not all of them!

The clunky gear change is a characteristic of a BEC as far as i know, no one i know has bothered with a cushdrive of any sort.

As for LSD, its a case of is the engine suited to the LSD or is the LSD suited to the engine, some bike engines are better suited to your most common LSD's (3.62) fireblade, R1, ZX9 will all go well with a 3.62 other nike engines have differing output ratios.

Do a search fo gear ratio calcuator on here and have a play about with diff ratios and different bike engines.
Thanks for that, I'll have a play with the gear ratio doo-dahs later.

I'm going to investigate the cush drive thingummy a bit more and report back. It strikes me that a bike gearbox and the clutch basket will be the weak points when putting a bike engine in a car and the cush drive on the bike is there (as I understand it) to save sudden shocks hitting these components.

I probably wouldn't bother except that I saw the remains of one of the cogs from the gearbox from the car I went out inyesterday and it had a massive chunk knocked out of it which looks like shock type damage rather than just wear. The car had been used for racing for a while so that could be partly to blame but I have no intention of giving the car an easy life

Regards,

Mark

Peteff - 11/10/04 at 01:41 PM

They don't make life any easier for the gearbox, they save the chain on a bike. I have a shaft drive bike and it doesn't have any cush drive. If you don't have the brake on hard when you select a gear it seems to go in easier.

dern - 11/10/04 at 02:08 PM

quote:
Originally posted by Peteff
They don't make life any easier for the gearbox, they save the chain on a bike. I have a shaft drive bike and it doesn't have any cush drive.
Some shaft drive bikes do have a cush drive to damp down the shock of a gear change. Some guzzis have the cush drive built into the clutch (dry clutch) and the honda pan-european has a damper in the drive shaft (no idea how that works) and a cush drive in the rear wheel for example(s). I'm not saying all shaft drive bikes have or even need one but it would appear that the use of one is not limited to chain driven bikes.

All the best,

Mark

dern - 11/10/04 at 09:28 PM

I thought I had a lot of decisions to make *before* I downloaded the gear calc program

As a first stab... 

code:
    GearCalc v2.0.0.3  Copyright ©2001, Peter Ogden 

    Gear Ratio, Speed and RPM Calculator 

 

    Gear set: Manually entered values 

    Gear        1        2        3        4        5        6      Final 

    Ratios:   2.692    1.933    1.600    1.400    1.285    1.190    3.620 

 

    RPM Limit:          7895 

    RPM @Peak Power:    6578 

    Tyre Size:          185/70 x 13 

    Tyre Diameter:      23.20 in 

    Tyre Circumference: 72.88 in 

 

 

    Gear   Mph per 1000 RPM   Mph @6578 RPM   Mph @7895 RPM 

    -------------------------------------------------------- 

      1         7.08                47              56 

      2         9.86                65              78 

      3        11.92                78              94 

      4        13.62                90             108 

      5        14.84                98             117 

      6        16.02               105             126


RPM is altered for a primary reduction of 1.52 which is what the blade/haynes book of lies says. My 929 blade revs up to 12k ish and max power is roughly at 10k ish I guess. I'd rather hoped for a slightly higher top speed at the limiter but the diff ratio of 3.62 seems to be available in LSD form without spending a ton. I'll have to see how big the arches are from MK and maybe go for slightly larger rears.

Complicated business eh?

Regards,

Mark

[Edited on 11/10/04 by dern]