Does anyone have experience with big singles in small alloy frames?

**koba** · 2nd May 2007, 21:31

I got a mutt off trademe! Cheap!

I dont mean to dribble but I think its the only way to explain my situation!

Its a Honda NSR250 frame and suspension etc...
But has a Kawasaki KLR600 single in it.

(check my profile for a pic.)

Its been pretty well built by someone (anyone know who?)

Its not all that fast but is basically a stock motor so there is a bit of potential there but considering my budget its probably just going to have to live with being slow! In its favour it has amazing cornering ability, although until I have a lot more race Km's behind me that wont matter much.

Anyway I was going to make a point!

Im aware there are a few of these type of things out there,
a couple of guys I was yakking to at my only time out on it at manfield had their own, one a RG/DR and i forget the other..

Unfortunatley i didn't then know I should ask them about engine mounting and vibration and if they could share their (probably secret) knowledge with me!

As far as I understand it a Vtwin (original motor) vibrates completley differently to a single and need to be mounted accordingly.
I have a plan in my head to add bits into the frame based on brainpicking I've done but wanted to get some feedback from as many people as possible, especially anyone who may have experience in this type of bike!

Any help greatly apreciated!

**Motu** · 2nd May 2007, 21:45

It will have a balance shaft and should be reasonably smooth.Are you sure it's a KLR600? They are pretty old,rare,and have problems.A better bet would be the much more popular and reliable KLR650.

**tri boy** · 2nd May 2007, 22:00

I mucked around with a Yam TT500 in an early RG250 frame.
It suffered from some cracks front and rear mount areas. But to be fair, I didn't spend much time perfecting the mounting system. Was a hoot to ride.

**koba** · 2nd May 2007, 22:05

haha yeah there is the catch..

KLR 600 so eligible for postclassic juniour.
It was made with balance shafts....
They are gone now...
Previous owner spent thousands getting them ripped out and having it balanced differently (I don't understand why..?)
He said it was unridabley vibratory (Engrish!) when he got it and that it improved when the work was done.
Maybe it was because it was known to have balance shaft probs..?
It is ridable as it is - just - but It cracked the (thin and inadaquate anyway) top engine mount - on the back of the head. Thats the main prob really, so I want to brace it differently but Im not convinced I know quite enough about what im doing yet...

**Sketchy_Racer** · 2nd May 2007, 22:06

Oh so many theorys on this.

Personally, the best i have seen, and seen the difference, is a mild steel 'subframe' for the motor.

teel is a far more flexible material than ally. it absorbs vibration a LOT better than ally.

Then there are theorys about putting sand in the frame etc etc... but those are just rumors i have heard.

Good luck i know that bike, and may be able to get some info about it for you

-Glen

**koba** · 2nd May 2007, 22:07

Originally Posted by tri boy

I mucked around with a Yam TT500 in an early RG250 frame.
It suffered from some cracks front and rear mount areas. But to be fair, I didn't spend much time perfecting the mounting system. Was a hoot to ride.

Anything you would have done to change the mounts?

**koba** · 2nd May 2007, 22:15

Originally Posted by RG100!!

Oh so many theorys on this.

Personally, the best i have seen, and seen the difference, is a mild steel 'subframe' for the motor.

teel is a far more flexible material than ally. it absorbs vibration a LOT better than ally.

Then there are theorys about putting sand in the frame etc etc... but those are just rumors i have heard.

Good luck i know that bike, and may be able to get some info about it for you

-Glen

Cheers my current plan is pretty much that.
7/8in steel tube with squashed ends from the front hanging mounts to the to rear subframe mounts initially followed by somthing more permanent if it has a positive effect.
Judging by the marks on the fucked mount The motor moves up and back so this tube should triangulate the frame and stop that hanging front mount from flexing up and back and rooting the head mount.
My big worry with that is if the rear subframe brackets can handle that plus my new head mount plus the rear subframe... thats a heluva lota shit for them little brackets to cope with!

**Sketchy_Racer** · 2nd May 2007, 22:23

Cool as... 7/8in tube.. comon man!! were not in the states..

I would probably reccomend some 25mm X 2mm thick Box tube.

And cutting some 'v's into the ends and welding them shut to get the flats to bolt onto the ally frame..

at a guess...

**tri boy** · 2nd May 2007, 22:24

Different compounds of rubber would have been one option. (and quite cheap)
Bracing suspect areas. Also Briggs and Stratton used to have a rpm tool for there stationary engines that would assist in locating frequency vibrations.
Talk to a mower shop. One of the mechanics may have one.

**koba** · 2nd May 2007, 22:31

Cheers guys.
I've still gotta talk to the original owner to see what info I can get on the balancing work done so i may be able to find the exact angle of vibration (so Im told!?)

Guess I will suck it and see anyway. hehe my neigbours love me!

Got lotsa bits n pieces to do on it yet but its a good mental exercise!
Learning HEAPS, any more comments, suggestions or whatever are more than welcome.

**riffer** · 3rd May 2007, 09:00

Hey dude,

not sure how much I can help but I'd love to come around and see this sucker!

PM me with your address details.

Simon

**cowpoos** · 3rd May 2007, 10:46

Originally Posted by RG100!!

Cool as... 7/8in tube.. comon man!! were not in the states..

I would probably reccomend some 25mm X 2mm thick Box tube.

And cutting some 'v's into the ends and welding them shut to get the flats to bolt onto the ally frame..

at a guess...

yep...and seal the box and fill with sand if you can...will take away heaps of vibs!!

**koba** · 3rd May 2007, 12:10

Originally Posted by cowpoos

yep...and seal the box and fill with sand if you can...will take away heaps of vibs!!

If its bolt on i can try both...

Keeping short with large cross section should help keep the resonant frequency thingy in a good range, I think! Its all a bit scientific for me...

Was It you who was bidding on it originally? (check my profile for a pic on it)

**cowpoos** · 3rd May 2007, 12:12

Originally Posted by koba

If its bolt on i can try both...

Keeping short with large cross section should help keep the resonant frequency thingy in a good range, I think! Its all a bit scientific for me...

Was It you who was bidding on it originally? (check my profile for a pic on it)

yep....I decided not to take it [it was offered to me after the auction never met reserve] after talking to him on the phone about it...he was honest about how quick it was...and I though it might have had more go that what he discribed...