It works! Low compression?
- Thread starter Noobi06
- Start date
How much squish should I aim for? Before you guys told me 0.8 but now that im there, you say it's too low. 0.9 maybe?
No, i do not know my overall compression but I am getting a new piston so I will be measuring piston clearance and then buy one. I also have a new piston ring.
How much piston clearance should I have? (mm between piston and cylinder wall)
No, i do not know my overall compression but I am getting a new piston so I will be measuring piston clearance and then buy one. I also have a new piston ring.
How much piston clearance should I have? (mm between piston and cylinder wall)
(F5)
Gold Level Site Supporter
Sorry if I confused you. I said 0.8 was ideal, but that's from an engineering point of view. It can't be taken in isolation. You get some movement in a running engine. If you set to 0.6 you would likely get the piston smacking the head which would be bad.
Whenever a tuner works an engine he sets the squish and then measures the volume at top dead centre (tdc). Then adjusts the headshape and volume to where he wants it.
There will be variation in engine to engine so you have to measure if you are seeking optimum. 2mm would likely be safe if you don't want to measure.
What we were trying to find out was if there was a dreadful mismatch of parts so like if you had 4mm squish or something completely wrong.
Maybe just maybe someone has machined the head before, but I wouldn't count on it. Thinking back, both my 200 and 300 had a black coating on the surfaces. Does yours? Is there evidence of some of it being machined off?
Perhaps the 125 is different.
I rode a 125 GasGas yesterday as it happens and it was very easy to kick over. But not the same engine as this was a Trials bike!
Whenever a tuner works an engine he sets the squish and then measures the volume at top dead centre (tdc). Then adjusts the headshape and volume to where he wants it.
There will be variation in engine to engine so you have to measure if you are seeking optimum. 2mm would likely be safe if you don't want to measure.
What we were trying to find out was if there was a dreadful mismatch of parts so like if you had 4mm squish or something completely wrong.
Maybe just maybe someone has machined the head before, but I wouldn't count on it. Thinking back, both my 200 and 300 had a black coating on the surfaces. Does yours? Is there evidence of some of it being machined off?
Perhaps the 125 is different.
I rode a 125 GasGas yesterday as it happens and it was very easy to kick over. But not the same engine as this was a Trials bike!
(F5)
Gold Level Site Supporter
For giggles if you have time here is an old thread of mine explaining the process of head mods.
http://gasgasrider.org/forum/showthread.php?t=16560&highlight=Head
http://gasgasrider.org/forum/showthread.php?t=16560&highlight=Head
You guys recommend I have around 1mm squish? I can fix that no problem, just increase the base gasket a tiny bit. Also my squish test was very quick, I can probably do it better and get a slightly different reading.
However when I google, my results say 0.8mm is ideal for a 125.
Edit: after some more googling, it looks like ideal is 1mm for road riding. If you want more performence like on tracks where you don't expect it to last, 0.8mm is ideal.
My engine needs rebuilding either way, so I will be doing that. After that I will be trying the same base gasket and I will do a real proper squish test. If its under 1mm, I will up the gasket till it is 1mm.
I will update you guys from there.
However when I google, my results say 0.8mm is ideal for a 125.
Edit: after some more googling, it looks like ideal is 1mm for road riding. If you want more performence like on tracks where you don't expect it to last, 0.8mm is ideal.
My engine needs rebuilding either way, so I will be doing that. After that I will be trying the same base gasket and I will do a real proper squish test. If its under 1mm, I will up the gasket till it is 1mm.
I will update you guys from there.
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One more thing. I got some issues and now my piston has a ton of vertical lines, however none of them can be felt by the finger nail. Is it a worry? It is a lot of lines but cant be felt.
Also if its no problem, will that piston last the same as a regular? around 100h ish.
I know you cant never know but still
Also if its no problem, will that piston last the same as a regular? around 100h ish.
I know you cant never know but still
Zman
Platinum Level Site Supporter
Please post photos of the head and piston. Can you feel a ridge at TDC (the top of the cylinder where the piston stops and changes direction)?
It is not uncomon to have some wear small scratches on the cylinder. It can mean that your air filter is letting debris and dirt past it.
It is not uncomon to have some wear small scratches on the cylinder. It can mean that your air filter is letting debris and dirt past it.
Ok, I will post photos once I get home. Im home at Thursday.
Reason why it has lines was because my bearings failed. Learned from my mistake once again, I tried to avoid changing the bearings even though I knew they had metal shavings in them. Literally after a minute of being started, once I took the engine out to do it properly, I noticed it already damaged.
Either way, Ill see how deep it is etc.
I will send photos and stuff
Reason why it has lines was because my bearings failed. Learned from my mistake once again, I tried to avoid changing the bearings even though I knew they had metal shavings in them. Literally after a minute of being started, once I took the engine out to do it properly, I noticed it already damaged.
Either way, Ill see how deep it is etc.
I will send photos and stuff
Exhaust port damage
I took some pictures of the cylinder today. I can not feel any damages on the bore with my nail, except for one horizontal line. However it is not deep at all, could barely feel it.
However, my exhaust port as you can see in the first image has a damage. How bad is that? Should that get nicasil replated, or is it okey, or?
I took some pictures of the cylinder today. I can not feel any damages on the bore with my nail, except for one horizontal line. However it is not deep at all, could barely feel it.
However, my exhaust port as you can see in the first image has a damage. How bad is that? Should that get nicasil replated, or is it okey, or?
(F5)
Gold Level Site Supporter
Ohh! Its cracked at the bottom of the bridge. Yes you must send it to be welded an replated. Most decent plating companies offer this sort of repair. Think US Chrome and Millennium if they are still what they were. Assuming you are in US. There are other reputable places.
Anders
Gold Level Site Supporter
As you are in Sweden, try to contact
https://www.blixtensracing.se/nikasil/utbytes-cylindrar-mxendruro/gasgas/
Sent fra min YAL-L21 via Tapatalk
https://www.blixtensracing.se/nikasil/utbytes-cylindrar-mxendruro/gasgas/
Sent fra min YAL-L21 via Tapatalk
Ah well. Thats not so fun. Either way. I will be sending both my cylinders (i got 2 gasgas now) for replating and welding.
I found a company in Sweden that does the job and gives me a kit (piston, ring, bearing, etc) for only 4300 SEK (400USD).
Also, I wasnt the smartest and didnt replace my bearings inside the engine even though they had metal shavings in them, so I will be opening it again and replacing them.
Also, one question. I want to wash the engine components when it is in pieces. Can I wash it or will I damage stuff? My dad told me we should wash it with diesel fuel so im asking you guys if thats a good thing to do or if we should avoid it or use another liquid.
Also is it bad to use water to wash? Is there anything I can't wash? Like the crank or the clutch plates?
Thanks guys
I found a company in Sweden that does the job and gives me a kit (piston, ring, bearing, etc) for only 4300 SEK (400USD).
Also, I wasnt the smartest and didnt replace my bearings inside the engine even though they had metal shavings in them, so I will be opening it again and replacing them.
Also, one question. I want to wash the engine components when it is in pieces. Can I wash it or will I damage stuff? My dad told me we should wash it with diesel fuel so im asking you guys if thats a good thing to do or if we should avoid it or use another liquid.
Also is it bad to use water to wash? Is there anything I can't wash? Like the crank or the clutch plates?
Thanks guys
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(F5)
Gold Level Site Supporter
Ahh sorry didn't realise you were from Sweden. That seems so cool to me. Total other side of the globe from my islands in South Pacific.
Good luck. Save up and be respectful to your father if he is paying for this. We try hard to be the right parent. But no-one gave is a manual of how to do this.
Good luck. Save up and be respectful to your father if he is paying for this. We try hard to be the right parent. But no-one gave is a manual of how to do this.
Zman
Platinum Level Site Supporter
Well said F5!
You can use Diesel, but low odor mineral spirits is probably a better choice. I have used mineral spirits to clean everything inside the engine without issues.
Using a soap/degreaser and warm water will clean the parts just fine, but then you need to fully remove the water and re oil the parts so they do not rust.
You can use Diesel, but low odor mineral spirits is probably a better choice. I have used mineral spirits to clean everything inside the engine without issues.
Using a soap/degreaser and warm water will clean the parts just fine, but then you need to fully remove the water and re oil the parts so they do not rust.
Okey. Then I will use low oder mineral spirits. And assuming the crank and clutch plates won't get damaged by it either.
Yes I agree F5. And don't worry, he won't be dissapointed. Im doing a street legal supermoto with this gasgas. Here in Sweden, they are worth around 6k-9k usd!
Yes I agree F5. And don't worry, he won't be dissapointed. Im doing a street legal supermoto with this gasgas. Here in Sweden, they are worth around 6k-9k usd!
