It's Winter Project Time! RXS100 Funtimes

[UnspeedySam]

So a lot has changed in the last few months...for those who care here's a breakdown

• Bought my Bros 400 in November and fixed it
  
• Passed my (33bhp) test in March after many weather and stupid mistake delays
  
• Graduated uni and got a job in June, commuting on my Bros
  
• Bros starts smoking like my old RXS on the way to the Brecon beacons in early September (2-up with camping gear on the M4)
  
• I need to buy a new bike for my tour in 2 weeks and get myself a ZZR600 and like a tool have it restricted the 'proper' way because we are going to Switzerland and I'm a woos

So I have 3 bikes and only the ZZR is on the road as my daily commuter...having covered in the region of 4000 miles on it in just over a month. The situation needs to be rectified!

The first thing I really need to do is get my old RXS back on the road, as my girlfriend is looking to do her CBT in the new year and needs a learner bike. What better bike to fulfil this task than my trusty Smokey.

The bike is complete but is slow and burning more oil than it should which I suspect is because it has done about 35000 miles on the original piston and rings (I have no actual idea of the bike's history). The electrics also need a complete overhaul.

I also have my friend's beyond repair '89 RXS which I am going to use for parts; buy off him what I use and help him sell what I don't use. I have already pinched the exhaust.

Here is the bike as it stands:
https://farm7.static.flickr.com/6052/6281027148_8d32a3bf1a.jpg
It had no grab rail or indicators there because I was mucking around, and the wiring and left rear indicator mount are both very broken.

TODO:

• Take a look at the engine and sort out piston, rings and/or bore
  
• Fix electrics and indicators
  
• Work out what I am going to do about the front end
  • Suzuki GN/GS125 or Yamaha RD125DX/RD200 front end
    
  • Use what I have and just replace the holey mud guard and get nice brake shoes
• MOT

____________________
Riding: BMW R1150RT `02 bought mildly crashed
Fixing: Also the BMW as I get less broken bits
Gone: ZZR600 '00, TRX850 '97, RXS100 '93, JS125-6B '07, BMW R1100RS '93, Kawasaki ZX-6R-J2 '01, Honda Bros NT400 NC25 '88

[UnspeedySam]

So first step is to finish taking my friend's bike to bits. It is already mostly just a rolling chassis. Tonight I got the engine out the frame and took the head off for inspection. Partially out of curiosity and partially to see what I have to work with if my motor turns out to be shot. Please bare in mind that I have no idea what I am doing and my knowledge of engines is minimal. I am doing this as much as a learning exercise as to build a solid learner bike for my girlfriend.

Note: These photos are not of the project bike, they are of the engine from the parts bike:

The head:
https://farm7.static.flickr.com/6117/6280558721_df450cedae_z.jpg

Barrel and top of piston:
https://farm7.static.flickr.com/6037/6280557253_ace61b0892.jpg

Barrel again:
https://farm7.static.flickr.com/6237/6281073426_47805e1ea2.jpg

It looks as if the head has partially melted as has the top of the piston. Although I haven't tried polishing anything yet...

It has done what I suspected was temporary heat seizing a few times due to the exhaust blowing the whole time he owned the bike. Does this look like damage from running very lean for a load of miles?

How bad does everything look to you people who actually know what you're talking about? I have no idea how scored an RXS barrel can be before it affects anything.

Next step: Take a proper look at the piston and rings

Opinions very welcome!
____________________
Riding: BMW R1150RT `02 bought mildly crashed
Fixing: Also the BMW as I get less broken bits
Gone: ZZR600 '00, TRX850 '97, RXS100 '93, JS125-6B '07, BMW R1100RS '93, Kawasaki ZX-6R-J2 '01, Honda Bros NT400 NC25 '88

[hazza]

When you say burning too much oil do you mean two stroke or gearbox? If it's the gearbox then it's going to be the crank seal bearings. I managed to change mine on my rxs without splitting the engine. If it's burning too much two stroke it's going to be the adjustment on the oil pump. Having said that a top end rebuild on that bike should take about an hour!
____________________
3 Honda NC50's(Sold)-->'72 Puch Maxi S (Sold, want it back!)--> '90 Yamaha RXS 100 (Stolen)--> '87 Honda Cub 90(Sold) --> '95 Kawasaki Eliminator (Sold) --> '98 Bandit 600 (Sold) -->'07 SV650S (Current)

[hazza]

The barrel on mine was about as scored as that! Used to run fine but the pistons needed replacing every 5000 miles though! rebore shouldn't cost much though. O and in terms of electrics what's wrong with them? It's a six volt system and was awful from the factory. The front headlamp is about as useful as a candle but swapping the bulb out for a halogen one can help a fair bit.
____________________
3 Honda NC50's(Sold)-->'72 Puch Maxi S (Sold, want it back!)--> '90 Yamaha RXS 100 (Stolen)--> '87 Honda Cub 90(Sold) --> '95 Kawasaki Eliminator (Sold) --> '98 Bandit 600 (Sold) -->'07 SV650S (Current)

[UnspeedySam]

[Welshd1k]

just sell me your can tbh
____________________
Current >Cb600fx hornet, ns125rk90 21.7bhp@wheel<
Sold >,zxr400 h2 (33bhp kit) rd350 n1 rd350 lc2<

[speedy]

the piston and head aren't melted its just the buildup of coke i think its called most of that should wipe /polish off
2 strokes are nice and easy to learn on
the excessive smoke may be down to incorrect jetting are there any after market bits on the bike ie pod filters etc?

[UnspeedySam]

I will have a go at cleaning it up tomorrow. It is the barrel I'm more interested inlearning the limits of. It has one quite noticeable ridge but the rest isn't noticeable to the touch.

My bike is completely standard. I have a hunch that the issue might have been down to the heat wrap I used to stop the old downpipe leaking; might have resulted in some overheating. Although upjetting might be an idea with the new spanny. I'll run some tests when I get it on the road.

Until then, I'll check the state of my top end in the next couple of weeks. I want to get it perfect anyway; if doing that sorts the problem then that's always good too
____________________
Riding: BMW R1150RT `02 bought mildly crashed
Fixing: Also the BMW as I get less broken bits
Gone: ZZR600 '00, TRX850 '97, RXS100 '93, JS125-6B '07, BMW R1100RS '93, Kawasaki ZX-6R-J2 '01, Honda Bros NT400 NC25 '88

[Shaft]

Before you do any cleaning up, you should spend ten minutes taking the top off your engine and compare the two.

You say you want to learn about what constitutes a good or bad barrel, that's probably the best way; the piston and barrel in the pics don't look too bad to me, but you'll only find out for sure by measuring.

You say the 'new' engine has only one noticable ridge, but what do you mean by that?

In my experience, the usual understanding of a ridge is what you normally get at the extremities of piston travel, around the circumference of the bore; if you mean marks running vertically up the bore surface, they are usually referred to as grooves or scores.

Might sound a bit pedantic, but it could be an important difference, when you're describing wear to other people.
____________________
Things get better with age; I'm close to being magnificent........
20 RE Interceptor, 83 Z1100A3, 83 GS650 Katana
WooHoo, I'm a Man Point Millionaire! https://www.bikechatforums.com/viewtopic.php?t=234035

[hazza]

Hi,

The oil pump regulates the feed of oil to the engine so if it's buning alot then it must need some adjusting. An air leak on the downipe wouldn't cause the pump to supply more oil. You are correct in saying it shouldn't need adjusting, but there's no telling what the previous owner has done. How much oil is the bike using?

Regards

Harry
____________________
3 Honda NC50's(Sold)-->'72 Puch Maxi S (Sold, want it back!)--> '90 Yamaha RXS 100 (Stolen)--> '87 Honda Cub 90(Sold) --> '95 Kawasaki Eliminator (Sold) --> '98 Bandit 600 (Sold) -->'07 SV650S (Current)

[UnspeedySam]

[TerraRoot]

for the oil consumption, try checking the cable, it sticks when you open the throttle and you don't notice it making the pump run flat out all the time, ask me how i know lol

https://terraroot.neoneoism.com/wp-content/uploads/2009/08/0803Image003.jpg

you pm'd me asking about the gs125 front end, i put that on because it was what i had, i'd not really recommend it, the stem needed lengthening by 1cm and i don't plan on changing the lower bearing any time soon. some grinding would sort that, lazily, i just left it as is.
https://terraroot.neoneoism.com/?p=313
all the info here: https://terraroot.neoneoism.com/?cat=10&paged=3 start at the bottom and work your way up

an rg125 16" front end fits great and has awesome brakes (i've no pics in digital) i did have some handling issues, but the trail was fine, if you keep the normal bars (mine was very front heavy) that option would be good.

[UnspeedySam]

[TerraRoot]

there's a difference in width so to make the gs wheel and forks fit you would first need to centralise the wheel by chopping bits off the spacers then you'd have to either space the disc out to centre it in the calliper or move the calliper, i can't remember weather the gs was narrower then the rxs or vice versa.

the rg front was quite stable, i used the rg yokes as well which gave the correct trail (very important) i had clipons installed with standard pegs and badly mismatched tyres, all that gave too much weight over the front and made it give way first, never fell off that way i just noticed it after a trackday on an rs250 and i was exploring the rxs's limits. it looked stupid but was the best front end i ever had and that included the massive disc'ed front end off an rxs135

[N cee thirty]

there's a guide on the yammy forum on how to fit a ybr front and rear end
____________________
'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[27cows]

That top end looks OK to me. Mine is much more scored than that, though it's done something ridiculous now, like 120,000 miles, so you'd expect it to be rough. Fact that it's still going, reliably, speaks for itself. Does it rattle much? Serious rattle on the overrun after closing the throttle at high revs is a sure sign that a rebore will be needed soon. Low rev rattle is common and nothing to worry about.

You can't tell by just looking at a piston and barrel if it's any good (unless something really obvious and catastrophic has happened). I've had heavily scored ones run lovely and perfect looking barrels and piston rattle about and run rough and horrible, lacking power. RXS100 motors do have a mind of their own. But it takes a lot for them to actually stop running.

GS125 yokes are a perfect replacement for the (pretty shit) originals with their stupid quick seize tops. But the whole front end is pretty much a non-starter. The RS125 front end will go on, but the caliper requires frequent tinkering to keep it working OK and it's not much more powerful than the original drum, so...

You used to be able to get soft compound brake shoes meant for (I think) ancient MZs. They worked brilliantly but wore rapidly and were expensive. No idea if you can still get those. SBS brakes shoes also work extremely well, as do Ferodo. Though EBCs aren't at all bad and last about 20,000 miles.

Can't see the point of putting a disc on, to be honest. Bike is so light and small that the drums do a perfectly good job. I've never failed to stop in 21 years of riding mine. Though if you had a YBR front end just sitting about, no harm in slapping it on there, I guess

Measuring things isn't worth the effort. My big end had double the max side to side clearance 70,000 miles ago and is still running fine.
____________________
The RXS100: vehicle of choice for Chuck Norris

[UnspeedySam]

[TerraRoot]

Don't give up on the disc, your girlfriend is on it, while i had the drum brake and could stop if i gave the lever a massive squeeze, it would fad away from heat and be useless for the rest of the day. no matter what shoes i used. One shock from a fucktard car driver and she'll quit riding, get her some brakes!
Just go around breakers yards measuring head stocks if it's roughly the right length it'll probably fit with some mixing and matching of bearing cups. try early yamaha tzr125s?
rg80 front ends are the same as rg125 front ends. most are worth nothing now buy a whole one with a dead engine?
or
just buy the right bike in the first place if modding the rxs is too hard for you?

[27cows]

I should of course have said 'stanchions', not 'yokes' in the previous post. Brain hadn't yet engaged at that point

35K is nothing is the motor hasn't been absolutely thrashed to buggery. But it might well have been. Without actually riding it and hearing what the engine sounds like and what kind of power it's still putting out, it's impossible to say what might need replacing. But if it starts easily, ticks over, will pull at least 65 on a flat road and isn't smoking insanely then chances are it's OK.

Previous top end went to 76,000 miles (.25 oversize, Taiwan piston) and never did stop running. It's pretty badly worn but would be put back into service in a crisis.

If the engine is smoking heavily and has lost power, rebore and new piston kit is the only way to go. A new piston would just rapidly wear if there's substantial wear in the bore. But I think a lot of people replace stuff when it's not necessary. My motor has rattled a fair bit since about 45,000 miles. But I just keep riding it (mostly quite carefully) and on she goes.

Stuff like RGV250s, the sporty 125s, off roaders etc - yep, they put out a lot of power and rings in particular wear fast and need replacing pretty often. But the RX was built to require the bear minimum of maintenance, and just soldier on and on while withstanding all manner of abuse and neglect.
____________________
The RXS100: vehicle of choice for Chuck Norris

[UnspeedySam]

[27cows]

I've used GS125 stanchions in the past (because they have hex head tops, and the standard of the chrome is better than on the RXS). They fitted straight into the RXS legs, and I kept the original RXS yokes on the bike. Used the GS springs, RXS damper rods. Didn't make any significant difference to the handling.

In theory, a GS front end should go straight on, using the RXS yokes. But the GS disc isn't exactly race spec. Can't see the small gain in brake power is worth all the hassle and expense (GS bits go for high money these days), unless you already have the bits knocking about.
____________________
The RXS100: vehicle of choice for Chuck Norris

[UnspeedySam]

[UnspeedySam]

[27cows]

[UnspeedySam]