NO COMPRESSION IN THE ENGINE

[minibuck]

i have DERBI senda 50 r 2000 i was riding with my friend and all of sudden my back wheel locks up i grab the clutch and free wheel to a stop i try to start it again but the kick starter was sold and would not move i got it into neutral and got the bike off the road i tried again to kick start it and it moved but there was no compression can i pls have some advice on what to do

thanks

[ThePhatomfart]

Hi, it looks like your gonna have to take the head off to have a look and see what the damage is, was the bike acting up before the seizure, and I take it's a 2 stroke

[Guest]

Hi, it looks like your gonna have to take the head off to have a look and see what the damage is, was the bike acting up before the seizure, and I take it's a 2 stroke

What spanner said

Derbi sender love eating pistons, do you pre mix or or rely on the pump?

[minibuck]

yea my bikes 2 stroke i don't pre mix my oil my bike has oil injection and yes for about a weak or so it struggled to continue to accelerate in 5 gear i thought maybe it was still warming up so didn't think anything about it but then my engine died so i'm gesing it the ring but haven't got round to taking the head of the engine yet and yes i let it run for about 5 minutes befor i road it to let it warm up

[Guest]

The pumps fail, more common is the filter gets blocked, also they don't mix very well. Pre mix will ensure its going in.

[minibuck]

i tuck the head of the engine and everything locked good the ring were still in place plenty of oil and no ovase cracks any were so i'm not shore whats wrong

pre mix my oil isnt relay an option for me because of the amount i use it every day i cover about 50 miles day so pre mix is relay feasible

[ThePhatomfart]

Hi , while the heads off try turning the engine with a spanner on the crankshaft nut to give you an idea of anything interfering with the stroke

[TimR]

Hi , while the heads off try turning the engine with a spanner on the crankshaft nut to give you an idea of anything interfering with the stroke

...not stupid but also see if the piston is actually moving as it should ie the con rod is still connected where it should be

[minibuck]

so with some day light and some more in dept in investigation the piston has actually collided with the barrel so i have got a new set of ring and a new piston but do i need to replace the barrel there is a small mark on the side of the barrel nothing mayor tho and you can berry feel it so should i replace the barrel or not bother

[Guest]

Get a barrel too, normally available as a kit

[Tango]

Yeah...replace the barrel too.....

[TimR]

For the piston to collide with barrel means that there is extreme play on one of its pivot points of the con rod

Check the big end bearings (crankshaft to connecting rod ) and the little end bearings (piston to connecting rod )

I would a either get a replacement engine

Or b if your going to repair its better off doing it all once

New piston ,barrell, rings, conrod and bearings and gaskets

You can hone small marks out of cylinder bores but i mean small without then reboring to a larger piston size bore

[ThePhatomfart]

For the piston to collide with barrel means that there is extreme play on one of its pivot points of the con rod

Check the big end bearings (crankshaft to connecting rod ) and the little end bearings (piston to connecting rod )

I would a either get a replacement engine

Or b if your going to repair its better off doing it all once

New piston ,barrell, rings, conrod and bearings and gaskets

You can hone small marks out of cylinder bores but i mean small without then reboring to a larger piston size bore

Just adding to what Tim says, wondered if you've suffered engine hydrolocking, if the conrod is bent that would point to that happening, as tim says the examination of parts will decide for you , but maybe look at a new engine

[acting_strange]

This sounds much more like a simple hot seizure to me....and as far as "colliding with the barrel" is concerned, this is what a hot seizure would look like to someone who has little to no knowledge (piston smears down the barrel).

Just a case of replacing the barrel, piston and rings, gaskets etc.

[minibuck]

i finally got the engine back together but it do not sound right and it not revving properly as when you get into anywhere near the power band it sound like it going to blow up it has compression, oil and flue

[Westbeef]

Did you replace the recommended parts, including the bearings?

[TimR]

i finally got the engine back together but it do not sound right and it not revving properly as when you get into anywhere near the power band it sound like it going to blow up it has compression, oil and flue

What did you find when the engine was apart ...?

If its been rebuilt don't go using excessive revs until its been run in ...

[minibuck]

the part were after market but not cheap nokeoffs they were supposedly proformace orientated

do you mean the bearings in the top of the crank arm as yes i did

i was only using what revs i need to get moving and even that was a stugeld as it would only get beryl to a high enouth revs to get moving