2 stroke engine rebuilds

[BUNGY]

Hi. Im looking at getting an rg150 but was told that 2 strokes need a complete engine rebuild every 10,000km. So is it true and if not whats the deal with engine rebuilds?

[svs]

probably don't need a complete rebuild every 10,000. Although it wouldn't hurt if you want to keep the engine in good condition.

2 kinds of rebuild.

1) Top-end. Replace piston, rings, wrist pin and bearings. Possibly head and base gaskets too. on an RG a piston kit costs around $300, $50 for base gasket and $150 for head gasket (suzuki prices). These can be had cheaper elsewhere.

2) Bottom-end. Replace bearings at crank end on conrod. Check and replace crank bearings. Probably doesn't need to be done as much as the top-end.

These are generally needed on all 2-strokes as the parts wear faster due to less lubrication - the only oil is in the fuel.

[Coyote]

As far as I know RGs need the top end done every 20,000kms. Mine is up at 34000 and hasn't had it done yet (resulting in it being very slow). I'm in the process of getting mine sorted. I just bought and oversized piston off trademe for 150 bucks (comes with everything I need except gaskets). Being oversized I need to get the cylinder bored (which I've been told should only cost 40 bucks, here's hoping), but in my case this is better than getting an expensive original sized piston then finding 34000ks has worn down the engine and it needed the bigger piston anyway. I've yet to get some gaskets and hopefully they won't cost too much (but after reading svs's post looks like they are). I'm going to do all the work myself (except the rebore as I don't have specialised equipment) which should save me a few hundred bucks in labour

I'll post up how it's going for me in here to help you along. Wellcome to the site :niceone:

[Kickaha]

Hi. Im looking at getting an rg150 but was told that 2 strokes need a complete engine rebuild every 10,000km. So is it true and if not whats the deal with engine rebuilds?

It wont need a complete engine rebuild at those mileages

The people who told you that probably ride four strokes, maybe rings and piston at that mileage but if you're prepared to put up with less performane you can easliy extend that considerably (as per alarumba's example)

using a good two stroke oil is a must if you want reliability and a good engine life



These are generally needed on all 2-strokes as the parts wear faster due to less lubrication - the only oil is in the fuel.

What? you don't even fill up the gearbox :bleh:

[svs]

What? you don't even fill up the gearbox :bleh:

Nah - don't need all that oil slowing it down :)


alarumba - take barrel to guys at hi torque (by guy weavers in paraparaumu). They're both racers and know what needs to be done. I got cylinder honed there for $20. Cheap, and a good job.

contact Henry at takanini motorcycle wreckers for cheap bits. I think that's probably who you bought the piston off anyway.

[Coyote]

alarumba - take barrel to guys at hi torque (by guy weavers in paraparaumu). They're both racers and know what needs to be done. I got cylinder honed there for $20. Cheap, and a good job.

contact Henry at takanini motorcycle wreckers for cheap bits. I think that's probably who you bought the piston off anyway.
The ride there will probably cost a fair bit in petrol though. I'll look them up though. Do you have their number or anything?

Yep, the dude of trademe was taka.mc

[Str8 Jacket]

My KR's done 33 000 K's now. Ive done 13000k's of those and it has'nt and does'nt need an engine rebuild.

*touches wood*

[k14]

My KR's done 33 000 K's now. Ive done 13000k's of those and it has'nt and does'nt need an engine rebuild.
Lol, famous last words.

How do you know it doesn't? Normally the only sign that it needs a rebuild is a loud bang and then a trail of metal pieces along the road after the piston explodes and takes the rest of the engine with it. Just need to rewind back 1km before that happens and do a rebuild then.

[Str8 Jacket]

How do you know it doesn't? Normally the only sign that it needs a rebuild is a loud bang and then a trail of metal pieces along the road after the piston explodes and takes the rest of the engine with it. Just need to rewind back 1km before that happens and do a rebuild then.

Well then it WOULD need an engine rebuild, would'nt it :blah: What I said was that mine has hasnt had one and right at the moment it doesnt need one even after 30 000k's. Was just trying to say that every bike is different! :nya:

Anyway bloody two strokes have little brains in them and will do what THEY want to do when THEY want to do it.

[FruitLooPs]

Well my RG150 is getting a complete rebuild right now. I got it with 46,000 on the clock so I guess you get that.

Turns out it didnt really need much done, I was fairly certain the seals were gone - but it turned out to be crankcase wasn't sealed properly from previous work done.

One of my questions before rebuilding it was exactly that, how long is it going to last. The guy who is doing my rebuild (oyster from here) has fully rebuilt around 15 of them and done the top end on plenty more and seen lots make 40,000kms without a full rebuild no problem with good maintenance. The ones that weren't looked after certainly had some funky pistons, pitting on the top of them, some with the rings melted to them, others with holes straight through the crown haha. He has been fixing RG150 streetstock race bikes for 3 or 4 seasons and typically they dont need any attention after being done once. Good oil is a must though, and get a temp guage installed since almost all of damage is done by people giving them goods before they're properly warmed up. The stock temp guage is completely worthless.

Mines getting an oversized piston too, as the cylinders been bored twice which is pretty unusual apparently. I'll see what the price is all up, but it wont be too bad as its had work previously. :yes: Much cheaper than through suzuki too. :blip:

He is also considering making powervalves in future which would rock considering the current prices for them :bye:


Very fun bike though, love mine to bits cant wait for the engine to come back. Mines got brand new powervalves too so it should be nigh on brand new engine wise hehe.

[Magua]

Good oil is a must though, and get a temp guage installed since almost all of damage is done by people giving them goods before they're properly warmed up. The stock temp guage is completely worthless.

Cover half of your radiator cover with masking tape or something similar, then you'll see the temp gauge move.

[FruitLooPs]

Yeah I know i've heard of that trick, might try it. I still will be getting a digital thermometer in place under the gauges as its not much and to me well worth knowing.

Another thing on the bikes is that the powervalves are almost always improperly set, and they also aren't reliable for actuating if you dont have a realllly decent battery, causes the tach to jump round too. That was what was up with mine in both cases and the first thing oyster asked was if it was a new battery.

I was annoyed because sometimes it would rocket off and be fine but usually it wouldn't hit the powerband, should be right after I get a new batt apparently. :yes:

[k14]

Well then it WOULD need an engine rebuild, would'nt it :blah: What I said was that mine has hasnt had one and right at the moment it doesnt need one even after 30 000k's. Was just trying to say that every bike is different! :nya:

Anyway bloody two strokes have little brains in them and will do what THEY want to do when THEY want to do it.
Yeah but the point i was trying to make is that it's impossible to "know" when a two stroke needs a rebuild. The only thing you have to adhere to is the manfacturers guidlines. There is no way of telling when it is going to blow up.

[Coyote]

I was annoyed because sometimes it would rocket off and be fine but usually it wouldn't hit the powerband, should be right after I get a new batt apparently. :yes:
Hey, that might be the problem with the valves on my bike. The battery for some reason will be drained after not using it for a while, requiring me to do an mx style flailing of the leg untill the neutral light brightens up again. After that, it'll take about 20-30 minutes riding untill it's sweet. I thought it was that it didn't warm up very fast, but it might just be the powervalves not moving very quickly due to the battery power being low

The other problem may be the clip holding the powervalve springs coming loose. I'll check that when I do up the top end anyway

[texmo]

And dont forget to check your piston return spring too rumba

[Deano]

A few hundred bucks every 10,000 km's could save more dollars every 20,00km's or so.

I rode my NSR250R hard for 26,000km's without doing anything to the top end. It gradually ran out of power and in the end it struggled to run at all.

When I stripped the top end, one piston had melted rings, a hole in the top, both powervalves were rooted, and my barrels needed boring and relining.

This added up to about $2000, but would likely have cost only $6-700 for pistons, rings and gasket kit, if I had done a top end rebuild at 20,000km's.

I ended up buying an import motor for $600, which was obviously quite fresh -getting on the throttle a little early had the bike drifting out wide coming out of corners.

If I was racing an RG150, I would consider a top end rebuild at least every 10,000kms, and possibly every season or two. (How long does it take to race 10,000kms ?)

[Magua]

Hey, that might be the problem with the valves on my bike. The battery for some reason will be drained after not using it for a while, requiring me to do an mx style flailing of the leg untill the neutral light brightens up again. After that, it'll take about 20-30 minutes riding untill it's sweet. I thought it was that it didn't warm up very fast, but it might just be the powervalves not moving very quickly due to the battery power being low

Shit, same thing happens here. I best look at getting a new battery.

[Coyote]

And dont forget to check your piston return spring too rumba
No need to worry, the shop said it was in perfect order. And I've had the crankshaft splines reticulated too. Don't want them to fail again