2 Strokes Down Under

Well there you go Pete, Lozza hates the 421s with a passion it seems and is entitled to his opinion of course, tho I know most 421s are not all or nothing machines, and Fred has a fast 250 which is cool.

Seems we are finding more fast 250s now which i think is supercool.

Pete, you have a nice original OEM bike there my choice would be to keep it close to original.

I would look more to emending it rather than full on moding. A few emendments like up the compression, squish band attention, chambers, bigger flatside carbs and attention to the electrics (and some suspension work) would give you a good streetable, enjoyable bike without breaking the bank.

If you are attracted to the challenge of a fully modded bike I would keep the current RZ and start with a cheap bitza and 'go mad' with 17's, USD suspension and the 421 etc etc.

That way you will be still riding while you are spannering and I don't think you'll be that far behind on cost.

Good point OLC, In fact I know of a guy who has an LC that has painted bodywork, a built long stroke 400cc LC(!) motor, a bunch of R6 stuff and 'all' (term used loosely) you'd need to do is finish it off. Ok, its not a beginner project and not cheap enough for the likes of most of us forumers who like a project to be <$1000 LOL, but with so much work done it would be fun to immerse yourself and solution the rest perhaps. Tis a thought.

JonW wrote:Well there you go Pete, Lozza hates the 421s with a passion it seems and is entitled to his opinion of course, tho I know most 421s are not all or nothing machines, and Fred has a fast 250 which is cool.

Seems we are finding more fast 250s now which i think is supercool.

I didn't say anything like that Jon The Athena kit promised a lot but didn't really deliver. Shits me that for all the effort they went to to do it but then make some really basic blunders. EVERY dyno graph from Athena kit bikes jump 30hp over a 1000 rpm as soon as they come on pipe. Fine if you want to go in straight lines.
Takes a fair bit of work to get the mid range back just to have roll on power.

I would second Ozzie's comments, your bike seems too nice to heavily mod, and if you keep your eyes open there are still good value bikes out there. You're going to spend on the motor anyway, a scruffy bike would be a great start point.

Hmm, you said it was 'shit' and a waste of money. My wife says that stuff about my bikes all the time, and yes she hates them with a passion. But I do take your point that it does have a step in power and does act more like an original LC say compared to the YPVS which is more linear, but that is expected.

These are 2 i just found, one is WinnerEvo's dyno, im seeing about 22bhp over 6-7k, and in Wicked's about 15. ie when the bike reaches its powerband, and pretty much 'as expected' I reckon. Looks more like a good way to woofle about in the lower revs in traffic and then when you get some open road to pin it and hold on. Maybe its more the way i ride LOL Ive never suggested that these bikes are for city traffic use, In fact I have specifically told Pete that if he wanted that he should buy a Scooter, and... he already has one, a Gilera 180. LOL





Im wondering if the percentage power gain between 6-7k revs is the same on a normal tuned (pipes etc) standard 350LC (ie the sans PV motor). I cant find any good dynos tho of sensible bikes, most have 20+ bhp there like the Athena does if they are MickAbbey tuned etc.

That massive jump in power you get from a power band is what makes 2 strokes such a rush to ride, I would rather ride an LC350 than a litre plus 4 stroke. Back in the day an LC was a great bike then the YPVS came out and made the delivery better but dulled the rush somewhat. If you can get better power and keep the YPVS like OZE suggests without going to the expense of a 421 then go for it but your considering going from a 250 YPVS to 421 non YPVS right, surely no matter what you do to a YPVS 250 it would never compare to 421 power?

Nice bike, would be hard to loose the originality of it if it were a 350.

Good luck with your decision.

Agree with bits of both Jon and Greasy, so long as its not unmanageable the power band kick is half he fun.
Mr Gailey could up he capacity to 350 and it's a natural upgrade, visually indistinguishable.
Gong to a 421 is changing the nature of he beast, usually done with more extreme bikes like Jons LC special, but could be a sneaky sleeper in what looks like an innocent RZ.

While it makes a nice machine, the problem for upping to 350 is the cost really, there is so much to buy for a proper conversion its crazy - see my site for the rundown on whats needed as I have done it, under the F1 buld I think.

Worse still is that a lot of 350 stuff is junk now. I mean, has anyone bought a set of 350 cyls and found the PVs useful in the past few years? I know I havent and Ive bought 3 sets (+1 for a mate) in 5 years and all needed new PVs. If you did then you were lucky, its not normal. I also found all the cyls I got needed a bore and new pistons, even tho the sellers said they would hone or reuse as they are. One set wasnt a set at all and one cylinder was ported and one not... just my experience, cost doesnt help tell you whats a good set sadly.

While an engine upgrade is not for everyone (and I still say you need to decide what you want the bike to do before you do anything), The Athena means you have all new parts and the costs are not far different than going to 350 if starting with a 250. Ive built both now and while they run different - the 421 sounds angry, the 350 even with PWKs and TSA pipes is muted and sounds friendly - Its the 421 that excites me the most.

While if you keep the old parts you can always go back if a restoration is needed later due to rarity or something, tho I fear that the resto value of an RZ250R is probably where its going to be already, for the forseeable future at least, so you may as well do it for you to ride and enjoy. None of these changes will make it look weird or wrong, just go faster. Those who followed my LC build will remember my LC can also be turned back into a standard LC if i had to as I have most of the parts to do that if i ever wanted, no cutting or welding of the frame has been done. Im never going to do it, but its nice to have the option.

Adding to what Jon just said, how often do the powervalves even come with the second hand barrels, usually they aren't even there.... what people do with them I don't know.
How much for rebores and jugs? My local place reckons about (above) $500 for. pair with Wossners.

350 cyls on a lowish bore would be $350-500 and they are usually in the uk, so factor in that postage. Pistons 200ish and rebores last time MRT did me them it was 77 a side, thats 150. Even at the cheapest, 350+200+150=700. Then you need to sort the chewed up (or missing) PVs...

If anyone wants to prove me wrong and find me someone selling a set of 350 barrels with good PVs that defo (engineer has spoken and refused to do it as its not needed etc) dont need a bore or hone and has usable pistons for 100 then PM me, I'll take em! ;(

Can't argue with much of that.
Hope Athena and equivalent stay around so the bikes can have a longer lifespan

2TInstitute wrote:....... spend it on decent suspension, tyres/wheels and brakes.

Thanks for all the input gents. Sure gives an old bloke plenty to research. Ive put progressive springs in the front forks, the rear suspension could probably be improved but the rear wheel is holding the road pretty well. Ive put twin triumph calipers on the front brakes, which incidently work a dream , plus Avon roadriders front and rear. I sort of like the standard wheels and think that's one of the reasons the bike handles itself well through the tight stuff. Ive pulled out the snorkel and put in a malossi red filter in the air box. I also spiked the exhausts and cut off half the baffles which did give the bike a sniff of aggression.

Jon asked me the question "What do you want the bike to do?" I didn't know at the time but its slowly coming into focus the more I research.

I want a bike that is two stroke smooth with kick when it goes on pipe. I want it to be good in the tight stuff, light weight, and I want it to have Yamaha reliability. I reckon Id be happy with the 350 upgrade if I could find a good one. I've been looking for 350 pots but have to agree with Jon on their rarity and shittyness. Sourcing the 350 option is turning out to be too erratic compared to the convenience of the Athena kit.

Ive worked the shopping list for the 421 option and a guesstimate is $5000+.

What I still need to look at is the go fast options I can do to a 250. What combos of pipes/ carbs/ porting are recommended for a 250? What about a 350 pipe?
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Got to go to bed!