Bought a Chinese 125cc :D

[Malt_Vinegar]

looks tidy, must be a good feeling to get it all refurbished!

Yup! Was great riding it to work for the first time. Always slightly nervous getting up to speed on something you have rebuilt! Nagging doubt you might have forgotten to tighten something or left something important off...

For £150 it wouldv'e been fine until the MOT ran out but you obviously know what you're doing and have some fun tinkering with it so regardless of it being chinese, I'd say it was worth the money

I'm half tempted to look and pick something cheap up myself to learn/tinker with

Do it! I am totally self taught, YouTube helps a lot and there is so much information out there on the net that you can't really end up stuck

Just remember that any job that can be done by a garage is done by normal people, and you are a normal(ish) person, you can learn to do it with a bit of reading and thinking!

Oh and there is a wealth of cheap and perfectly useable tools out there that you can get in a couple of days from the usual places. So if you can't bodge it simply, get the proper tool, and it becomes easy.

 

[Malt_Vinegar]

Finally managed to get a finish on the side panels that I liked after quite a few coats and a couple of sanding sessions.

Not perfect, but I know enough now to make it work on other panels when/if I get a nice bike.

Used bumper repair paint in the end as it seemed to be tougher than most.

Just working on the footpegs now. Tidied up one of the passenger ones and gave it a quick blast of clear to help stop oxidation going forward. Removed the rider ones tonight and will use the same method on them with a few improvements. Should look nice and clean again.

Sneak peak at the first cleaned up one vs an untouched one.

 

[Malt_Vinegar]

Just an update on the bike.

About 200 miles in now, many rides, and has been reliable so far. I got some new (more) mirrors, which caused an issue, as one of the threaded holders was knackered, Ran a tap through it, but it was not playing ball. So I epoxied it in, and seems to be working fine so far. Having the full sized mirrors really makes riding feel a lot safer.

I think I will drop the oil shortly, as the engine should be bedded in now with the new parts, and just trying to work out what sort of oil is best! Clearly, i need a motorbike oil as I have read about the gearbox requirements so just nicking some from my car supply is out of the question.

Castrol 4 cylinder stuff seems highly rated, so will probably go that way. Filter was purchased ages ago in anticipation of this.

Really enjoying riding, but need to work on figuring out grip levels, as I am being ULTRA cautious when the road is damp!

 

[tom_e]

If You've got decent rubber then road grip when damp/wet isn't that far off dry to be honest.

 

[Lopéz]

Looks smart, nice job!

 

[Malt_Vinegar]

Looks smart, nice job!

Cheers!

This was a little while ago now, as per the "stuff you did to your bike today thread" post I made at the time.

However, in true OcUK fashion, you guys we correct! The valve (intake) that I did not replace because I figured "If it ain't broke, don't fix it" lunched itself in very unspectacular fashion:

It slipped its collet, dropped into the piston, and smashed itself into the valve guide, which had a hairline crack. So i decided to refit a new valve, and see if it would still run.

It does run again, but sounds a bit funny at higher revs and is not liking trying to go over 6k, which I think is symptomatic of the cracked valve guide. Still, I know it works, and think I know what is wrong... SOOOOO - new plan!

I don't fancy replacing the valve guides, so lets replace the original head with a Suzuki GS125 head, with new valves included for £60! (oddly cheaper than the Chinese spare part??)

Now, it MAY work with the flat top piston that I have in there already (which survived remarkably well for being whacked), but compression might be a tad too low, as the GS uses a domed piston.. I do happen to have a domed piston as part of the kit I got with the Suzuki cylinder I already replaced, so, I will probably swap those over while the engine is split. MIGHT actually get me a bit more compression, and perhaps a slight performance increase.

This is all provided the head will fit, but as its already on a Suzuki barrel, I have high hopes



So, what did I learn? If you can replace a part whilst doing similar parts, do it... It saves time, money and hassle in the long run Also, if you have a K157FMI engine, replace the valves and associated parts.

Also, when I replaced the bent valve, I actually managed to do the work with the block still in the frame, so its much faster. I also did the whole rebuild a LOT faster than the first time. Should be able to get it done in about an hour this time. So, i guess at least I am getting more proficient at rebuilding small 4 stroke engines

 

[Diddums]

Always, always replace wear items when stripping stuff. Saves you stripping it all again.

 

[Malt_Vinegar]

Always, always replace wear items when stripping stuff. Saves you stripping it all again.

Yup, I know that now! HOWEVER! At least I get to get greasy again

 

[Malt_Vinegar]

Bike now has a Suzuki Head/Valves/barrel and piston. I also replaced the valve locks at the same time, as they were looking a bit worse for wear.
Took it out for a ride today, and it feels good. Didn't go far as I think I needs the valves adjusting.
I think its going to be a tiny bit quicker, as it has more compression, domed piston, and larger valves/ports.
It's never going to set the world on fire, but I think I might ride it for a bit, then see if I can find an old Honda 125 or something to have a play about with.

 

[jigger]

You have done one hell of a job with the bike. Bummer about the dropped valve.

 

[Malt_Vinegar]

You have done one hell of a job with the bike. Bummer about the dropped valve.

Haha, thanks
Its been fine for a bit. Ridden it to work a few times, done a few longer rides and been enjoying it.

Topping out at 55/56 and I need to make a better seal for the tacho drive in the Suzuki head. The plastic bushing I used as a spacer is warping in the heat and needs tightening up after a long ride.

To stop valve slap on the motor with the slightly taller Suzuki piston I had to make the barrel sit higher by buying some thicker gasket material and tracing/cutting a taller one to replace it.

I toyed with the idea of running a doubled up head gasket to increase the head height but it just looked too much to ask for a decent head seal under combustion with that setup. I did try it breifly and it held for a bit, but mainly I used it to calculate the height needed to stop the valve slap.
I think there may be room to extract some more power if I lower the height a bit, but it's running reliably so I am leaving it for now.

 

[jigger]

Haha, thanks
Its been fine for a bit. Ridden it to work a few times, done a few longer rides and been enjoying it.

Topping out at 55/56 and I need to make a better seal for the tacho drive in the Suzuki head. The plastic bushing I used as a spacer is warping in the heat and needs tightening up after a long ride.

To stop valve slap on the motor with the slightly taller Suzuki piston I had to make the barrel sit higher by buying some thicker gasket material and tracing/cutting a taller one to replace it.

I toyed with the idea of running a doubled up head gasket to increase the head height but it just looked too much to ask for a decent head seal under combustion with that setup. I did try it breifly and it held for a bit, but mainly I used it to calculate the height needed to stop the valve slap.
I think there may be room to extract some more power if I lower the height a bit, but it's running reliably so I am leaving it for now.

The compression ratio is probably a little low. You could maybe get the top of the piston machined for clearance if it's close.

 

[Malt_Vinegar]

It's a domed piston, so can it still be done?

I think perhaps just making a slightly shorter gasket is worth a shot when I next have the engine in bit

 

[Malt_Vinegar]

Well, I moved it on again last night for £250. It dropped a valve again on a shopping trip. I had bought performance valve colletts when i rebuilt it to replace the knackered ones. But I think the engine decided they were too good for it and spat one set out.
Still sold it on, learned a lot from it. Now saving up to get me an old Honda 125 or something to have a go with over the winter

 

[The_Abyss]

This news prompted me to review the original replies to the OP on page one. There are some gems of wisdom there

But I think I like the last one from @Diddums the most, countering them all

Perhaps it just wasn't to be - certainly must have learned a lot from all the work.

 

[Malt_Vinegar]

Haha, indeed. It was always a learning exercise though. And I have already used the things I learned on my other bike and am now itching to find something more Japanese to play with.

 

[vanpeebles]

Diddums should straighten the bent value with his teeth

 

[Diddums]

This news prompted me to review the original replies to the OP on page one. There are some gems of wisdom there

But I think I like the last one from @Diddums the most, countering them all

Perhaps it just wasn't to be - certainly must have learned a lot from all the work.

I'm lost, which post? I have like a billion posts per page (give or take).

@Malt_Vinegar you did well, let's be honest you bought it pretty much for the sole purpose of messing around on and learning, I've no idea what you've spent on parts & time but you've managed to sell it for a £100 profit so that should Shirley negate some of the parts prices. This is exactly what spannering is all about, learning as cheaply as possible and then moving on to other projects. Despite it regurgitating valves I think you did well.

@vanpeebles I'll do it. Send me the valve and I'll do it.

 

[Malt_Vinegar]

@Diddums Yup, I will admit to being a little disappointed I did not prove everyone wrong. But I stand by the fact that if these are looked after from new, they would be MUCH more reliable. The problem is, they are bought new for sub 2k, sold on even cheaper, and people treat them like cheap throw-away items.
Would I buy one new, if I was on a budget, yes. Certainly. Drive it under warranty, give it some love, and it will do the job fine for all but the most hardcore 125 rider.

I think this was more of an uphill battle, but I suspect it owes me about £50 after parts, if I count up. Happy to swallow that for what I learned