CHEETAH CUB: YAMAHA RD421LC RESTOMOD / HYBRID

[Skub]

https://www.bikebound.com/2023/02/22/ch ... mhide=true

Sounds like a handful on paper,nevermind riding!

The engine is now a 421cc with a +4 mil TSS crank, Cheetah Cub barrels, and 35mm Air Stryker carbs, as well as a whole host of other modifications including a hydraulic clutch. The pipes are also handmade by Performance Fabrications

[Rockburner]

That massive tail unit looks wrong.

Lots of work though.

[mangocrazy]

There's a lot about that I really like, but as RB says, the tail unit is just wrong - too high, wrong angle, too long. I'd also question the need for 6 pot ISRs - a pair of 4 pot, 4 pad Goldline Brembos would be more than enough and save a fair bit of unsprung weight. And while I applaud him sticking with the original 4L0 350LC motor, dropping a YPVS in the frame would have been the smarter move, I think. I also can't fathom how he gets 95 rwhp with 'standard porting'. The spannies look great, but are a bit bulbous and look as if they might ground out if taken to a track (or even ridden with brio on the road).

But all in all - nice one. I approve.

[Demannu]

Not enough pinstriping.
I think when he says 'standard porting' he means cheetah rather than Yamaha!

[weeksy]

Awful.... nothing i like about it... but that's not a surprise to anyone.

[Taipan]

I should like it, but I don't. If you're going to use black and yellow, do the KR speedblock thing.

[Le_Fromage_Grande]

I don't see the point of LCs that make more than 60 bhp, they're never pleasant to ride, and there are lots of easy ways to get a 100 bhp.

[Bustaspoke]

I don't see the point of LCs that make more than 60 bhp, they're never pleasant to ride, and there are lots of easy ways to get a 100 bhp.

I agree, & god knows how much time & money has been spent on it...

[Yorick]

I don't see the point of LCs that make more than 60 bhp, they're never pleasant to ride, and there are lots of easy ways to get a 100 bhp.

My F2 LC350 made about 60 BHP and was a real hoot to ride. Often went to work on it for a giggle

[Le_Fromage_Grande]

I don't see the point of LCs that make more than 60 bhp, they're never pleasant to ride, and there are lots of easy ways to get a 100 bhp.

My F2 LC350 made about 60 BHP and was a real hoot to ride. Often went to work on it for a giggle

I had a YPVS that made about 70, it was much nicer when it made 60, and now I'm happy with a standard ported one, there are easier ways to go fast than a 40 year old 350 two stroke.

[mangocrazy]

I don't see the point of LCs that make more than 60 bhp, they're never pleasant to ride, and there are lots of easy ways to get a 100 bhp.

My F2 LC350 made about 60 BHP and was a real hoot to ride. Often went to work on it for a giggle

I had a YPVS that made about 70, it was much nicer when it made 60, and now I'm happy with a standard ported one, there are easier ways to go fast than a 40 year old 350 two stroke.

If you go down the large capacity YPVS/Banshee route you can have your cake and eat it - lots of power, rideability and reliability. And to say 'there are easier ways to go fast than a 40 year old 350 two stroke' is missing the point entirely. But then you knew that.

[Bigjawa]

Could have been lovely, except it's hideous.

[GuzziPaul]

Another vote for the horrible seat unit. I would prefer a more standard look/street sleeper. Do the wheels and supension but keep it looking standar ish.

[Le_Fromage_Grande]

My F2 LC350 made about 60 BHP and was a real hoot to ride. Often went to work on it for a giggle

I had a YPVS that made about 70, it was much nicer when it made 60, and now I'm happy with a standard ported one, there are easier ways to go fast than a 40 year old 350 two stroke.

If you go down the large capacity YPVS/Banshee route you can have your cake and eat it - lots of power, rideability and reliability. And to say 'there are easier ways to go fast than a 40 year old 350 two stroke' is missing the point entirely. But then you knew that.

They're not reliable, 70bhp LCs eat cranks, and I doubt if a pattern stroker crank is as well made as a Yamaha standard crank, TZ350s also go through cranks when they make 70bhp, and as I've said, I don't see the point of engine tuning on an LC now, the only reason I did it in the 80s was because I couldn't afford to run anything bigger and faster than an LC, as soon as I could afford a GSXR750 I bought one, it was a massively better bike than my YPVS.

[mangocrazy]

I had a YPVS that made about 70, it was much nicer when it made 60, and now I'm happy with a standard ported one, there are easier ways to go fast than a 40 year old 350 two stroke.

If you go down the large capacity YPVS/Banshee route you can have your cake and eat it - lots of power, rideability and reliability. And to say 'there are easier ways to go fast than a 40 year old 350 two stroke' is missing the point entirely. But then you knew that.

They're not reliable, 70bhp LCs eat cranks, and I doubt if a pattern stroker crank is as well made as a Yamaha standard crank, TZ350s also go through cranks when they make 70bhp, and as I've said, I don't see the point of engine tuning on an LC now, the only reason I did it in the 80s was because I couldn't afford to run anything bigger and faster than an LC, as soon as I could afford a GSXR750 I bought one, it was a massively better bike than my YPVS.

I'm sure that was absolutely the case in the 1980s, but we're now in the 2020s and metallurgy and lubrication technology has moved on massively. I was talking to Dave Whattams about this last year, and he was adamant that well over 70bhp can be obtained from a 350YPVS without any loss of reliability. The problem of course is cost. For the price of a fully specced 350 YPVS motor you can buy a secondhand 120 bhp motorcycle and probably still have change.

[Le_Fromage_Grande]

They don't take a lot of money to get to 70bhp, a good porting job and exhausts will do it, just, 34mm carbs would guarantee it, you'd also need a new ignition on anything other than a 31K as the later bikes have rev limiters, mine never broke down, but the crank had play in the main bearings after a couple of thousand miles of revving at 11000 rpm, I think the standard bikes don't have any power at over 9500, mine only made power once you were in the red line, it was a much nicer bike to ride when the power was lower down. I suppose it depends on what you want, my experience of the LC Owners Club these days is middle aged blokes standing round at bike shows telling people how much power their LC makes, much like the eejits with turbo nitrous Z1000s, I really don't want to ride a 1978 bike with 230 bhp either.

[mangocrazy]

I really don't see the point of going for a great deal of extra power on a 4L0 350LC; the frame, forks, brakes and swingarm can tie themselves in knots even with standard power so more power in a standard setup is not a wise use of funds. In my (lottery-funded) dreams I'd like a tricked out 421cc YPVS motor in the Hejira chassis I sold on over 20 years ago, but it ain't gonna happen.

Hejira_01.jpg (51.97 KiB) Viewed 1123 times

[Bigjawa]

I really don't see the point of going for a great deal of extra power on a 4L0 350LC; the frame, forks, brakes and swingarm can tie themselves in knots even with standard power so more power in a standard setup is not a wise use of funds. In my (lottery-funded) dreams I'd like a tricked out 421cc YPVS motor in the Hejira chassis I sold on over 20 years ago, but it ain't gonna happen.


Hejira_01.jpg

This, look at the frame at the swingarm pivot, you've got a hugely stiff swing arm and front end and the middle is still pure 1970s* design small diameter tubing. You're just transferring the stress elsewhere.

*I know the LC came out in 1980, but it has more than a touch of 70's TZ in the design.