LCGB Forums

Hi guys
I am in the process of running in a 125cc bored out to 175cc,problem is I managed to seize it on a long straight,to be fair I was probably pushing it too hard,question does anyone think I should check the cylinder and piston or does anyone think it will be ok thoughts ??
Cheers in advance

I'd check it out if I were you. How many miles have you done on it so far and what is your running in schedule? Holding it in the same throttle position on a long straight really isn't the best thing to do when running in

Only up to about 120 miles at the moment,usually just potter about around town for 30 mins or so going through the gears as much as I can,however I couldn't resist a little open road and was probably just a little too long and fast on the throttle in fourth gear,what would you suggest ??

If it still kicks over and starts I'd just ride it. But richen up in the throttle area it seized in.

Cheers guys,I'll keep my fingers crossed and my impulse to speed too soon in check from now on

125 bored to 175 ??

Donnie wrote:125 bored to 175 ??

That was my thoughts too........

In the late 1960s I had an Li 125 which I had bored out to 150. To start with it would seize quite frequently but I got the knack of pulling the clutch, coasting for a few yards then releasing the clutch to bump start it. It settled down eventually. Should I really have admitted that on here?

^... I used to do the same but changed my approach when I did the same on a DL150 riding back from Rimini and let the clutch back out and broke my piston rings... in the middle of nowhere in France. Considering the massive stress that this approach puts on the rings, crank, etc. I'm not surprised in the damage that resulted and have since changed my response to a nip up.

Adam

My theory is,if it starts first,second or third kick immediately after the seize,ride it like nothing happened,
upjet like Eden said and forget about it

Funny you should say that. I had a 128 main in my iron 225, thrashed the granny out of it for 20 motorway miles before soft seizing, upjetted to a 132 & it was too boggy, so put a 130 in & it's still not as responsive compared to having a 128 jet in, but it sat at 55-60 all day for C2C. Slightly disappointed at the little nip up as it was banging along on the 128.

Sorry guys,just to add to previous post, 150 cc bored out to 175 cc ,registered 125 cc ,again thanks fellas she kicked over first kick after soft seizing and trundled home no bother so will see how she goes, will treat her gently from now on

seized my Rapido on the C2C. Thought it was terminal and phoned my lad to come and pick me (he's on 24 hour call during rallies ). After waiting 20 minutes I thought i'd try kicking it over.......I was surprised when it fired up. I cancelled lad and completed C2C, which was another 300 miles. Took the barrel off yesterday and the piston is pretty messed up, small piece missing on the side, rings stuck in, bits of piston in the crank area, and I don't think I will be re-fitting it. Barrel not too bad though.

My point being, even if it runs after a sieze it i'd have a look inside.

Had the same problem with my SX when running in. Even though it kicked over straight away and drove home with no problems I checked out the piston and barrel which seemed ok. I was then advised by a scooter engineer to check gap between piston and barrel which he said was 1 thou and too small so had it increased to 3 thou and never had any problems since and has never let me down at what ever speed I go.

Some sizes do more damage than others. It all depends if you feel it coming and grab the clutch before it actually locks up. If the seize with no load like this it's rare to have damage but if you don't feel it coming and it locks up while your still pushing it at wide open throttle there can be lots of damage.
Every seize I've ever had has been after I've grabbed the clutch. You can hear the engine note change when the pistons getting tight and you can also feel it too.

I remember years ago a guy ridding with us one day who didn't have much ridding experience put his left hand up to let us know he felt a problem coming on while ridding wide open in to a head wind, just after putting his hand up his engine locked up and threw him off as he was unable to get his hand back to the bars and grab the clutch in time. When ridding hard I always from time to time clutch in and let the revs drop to give the engine the oppertunity to size while under no load if it wants to. If it doesn't size I clutch out and carry on then do the same a few miles later and so on.

I would increase the idle tick over to 1000-1200rpm
When you deaccelerate at speed and close the throttle your engine is still spinning at 4-5000rpm driven by the wheels yet your carburettor is only supplying sufficient fuel for maintaining an idle speed .
Guess what happens to the engine temperature !?
Check your plug colour and make sure that it is a nice chocolate brown colour rather than the usual soft brown .

The absolutely critcal thing when running in any engine is never to stay at the same rpm . It doesn't matter what speed you do its largely irrelevant. The crucial thing is what rpm the engine is doing. Just vary the rpm and it should be fine.

Eden wrote:Some sizes do more damage than others. It all depends if you feel it coming and grab the clutch before it actually locks up. If the seize with no load like this it's rare to have damage but if you don't feel it coming and it locks up while your still pushing it at wide open throttle there can be lots of damage.
Every seize I've ever had has been after I've grabbed the clutch. You can hear the engine note change when the pistons getting tight and you can also feel it too.

I remember years ago a guy ridding with us one day who didn't have much ridding experience put his left hand up to let us know he felt a problem coming on while ridding wide open in to a head wind, just after putting his hand up his engine locked up and threw him off as he was unable to get his hand back to the bars and grab the clutch in time. When ridding hard I always from time to time clutch in and let the revs drop to give the engine the oppertunity to size while under no load if it wants to. If it doesn't size I clutch out and carry on then do the same a few miles later and so on.

I had a similar experience a few years back, scooter had a habit of flooding (Jetex 22mm) and I took the filter off to start her up but then forgot to replace it. Had about a 20 mile ride home and was sitting there at around 55-60 and felt it going but mistook it for running out of fuel so left hand off to flip over to reserve when it locked up. What made it even worse was that the road has recently been re-surfaced with loose chippings and I was going round a slight bend. Managed to get my hand up to the clutch and just about stayed on but it was a close run thing! Started up straight after and did a load of miles over the following 2 years before I finally killed it, TV200 barrell snapped a ring, but it was on it's last re-bore anyway and has had a full restore