My bike can be started by hand. It's so easy it's unreal. To me probably being naïve, this is brilliant! I have since been told this is not a good thing and means there is no compression. I do not have a compression tester. Does this mean it wants sorting? I've also been told this will help the performance a lot?!?
Cheers,
Dan
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if i can't fix it with my lump hammer, it's electrical.
if you can start it with your hand, then compression is wayyyyyyy down
yes you should probably do a top end rebuild! if you do it yourself you save alot of money, cost about £100 in total, maybe abit less. the only problem is with you running it in, you dont want to potter around a field for hours and hours on end, its about 500 miles to fully run in a piston, but i think your going to have to be quicker than that.
being a field bike, just wait until it goes pop cuz you will be immensey bored!
every dt i have ever ownd you could start by hand even a freshley rebilt one why not just put a new piston in without reboreing it saves gaskets aswell as you dont have to replace the head one
hmmmm not sure tbh mate, best if you could find a compression tester ..
if you rebuild it you will have to run it in (can you really be arsed?) if you dont rebuild it, it will be down on power abit but will still run fine, id be tempted to just rebuild when it dies.
from what i believe, when you run them in, you do it to prolong the life of the piston, with this being a field bike, could you not cut down on the running in time as i dont see me needing to get much more than 1000 miles or so out of the bike itself??
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if i can't fix it with my lump hammer, it's electrical.
running in the piston properly prolongs the life and gives you more power.. yeah you can just do that, not run it in, wont last as long but you dont need it to
yes mitaka is a good piston brand.. but your going to have to take the barrel to be measured at a garage, to see if 1. it needs reboring 2. if the guy who owned the bike b4 a pikey nicked it had it rebored lol. Then you will know what size piston to buy. Email PJmotorcycles and ask for a small end bearing comes with the piston kit (dont think it will do! and also circlips)
a lad i know with a field bike last time he run it in, on tickover with one tank of fuel then another tank with some revs (bout half turn up using tickover screw on carb) then rode it. Its been running for a fair while on the same piston now, dont know how much he uses it though. As for finding out piston size but a verynear calliper off ebay and measure it yourself and post up pics of the barrel and we can tell you if it needs reboring ;)
not the best thing to do the idear of running in is to bed the rings into the barrel by puting load on them if you let it tick over the rings wont bed in properly and you will lose power
Robin im fully aware of the puprose to running bikes in but this is a field bike we're talking about. He doesn't want to pootle around for days on end to run it in, if he was to go round the edge of a ten acre field once he wont of done half a mile so hes going to have to pootle round the a field with no clocks to tell him how many miles hes done It would take an age. But if he does it the way i said he can just leave it runinng. If you think about to run a bike in right you do so many miles at say 4k revs then gently increase to 6k rev for so many miles etc etc. If you do it the way i said but work the revs up slower then your doing the same without having the chore of running it in the 'proper' way.
Benefit of my experience running in two-strokes... assuming new piston rings on a honed or rebored cylinder - half an hour at mid revs, half an hour at mid to high revs, half an hour using full rev range. Job done.
The whole idea behind running in is to get the piston rings to seal good with the cylinder, and the only way to do this is to load the engine. You have a small window of time to do this, if you don't you might as well strip it down and start again cos it'll never bed in otherwise. Don't scream it in first and second, use these gingerly for the first 90 minutes or so, but pull hard (open the throttle) from third gear onwards, keep the revs varied.
The 500 miles thing is a myth - its recommended new bikes/engines are run in for 500 miles as a good way of getting you to take it easy until you "know" your bike a bit better. If its gonna go tits-up it'll do it whether you take it easy or not.
Running in a four stroke is even beter fun!
-- Edited by Malc on Saturday 10th of April 2010 05:17:51 PM
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Just because I don't care, it doesn't mean I don't understand...!
if you can start it with your hand, then compression is wayyyyyyy down
yes you should probably do a top end rebuild! if you do it yourself you save alot of money, cost about £100 in total, maybe abit less. the only problem is with you running it in, you dont want to potter around a field for hours and hours on end, its about 500 miles to fully run in a piston, but i think your going to have to be quicker than that.
being a field bike, just wait until it goes pop cuz you will be immensey bored!
Just heat cycle it 3 times. You only run a bike in when they're new as things like the gearbox, tyres & brakes need a certain amount of time to bed in. If you are only doing a top end rebuild it's not necessary to do loads of miles.
BenR Can you explain what you mean by 'heat cycle it'?
There is no need to "heat cycle" a new engine. The term "heat cycle" comes from the idea that the new engine components are being "heat treated" as the engine is run. Heat treating the metal parts is a very different process, and it's already done at the factory before the engines are assembled. The temperatures required for heat treating are much higher than an engine will ever reach during operation.
The idea of breaking the engine in using "heat cycles" is a myth that came from the misunderstanding of the concept of "heat treating".
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Just because I don't care, it doesn't mean I don't understand...!
i found on two top end rebuilds, 2K miles was full bedded!, 600 miles was the limit of extended revs for a long periods. Short sharp blasts is the way to go, if ya beat the living daylights out of it, then back off the throttle and rev down in 6th.. its gona seize on a fresh rebuild.
took bloody ages before my fresh rebuild was ok. It went like scalded cat tho, power is awsome. Mind u 1mm skim off the head too..compression is loverly!
now im building my new engine.. n do all over again.
Just heat cycle it 3 times. You only run a bike in when they're new as things like the gearbox, tyres & brakes need a certain amount of time to bed in. If you are only doing a top end rebuild it's not necessary to do loads of miles.
