New problem and I can’t figure it out – Hyosung GV250
- This topic has 15 replies, 3 voices, and was last updated 11 months ago by
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Okay so I was riding down the freeway doing 85 all of a sudden I lost power bike won’t go over 35 I was 2 exits away from where I was going so I threw on my hazards. I checked hoses those seem to be good I did notice I lost a cam chain tensioner nut the middle one.my cam chain was loose and and It had skipped a couple links so I ended up getting the motor back to how it should be thinking that would fix the problem it did however get ride of the ticking noise but I still can’t get the bike over 30 any ideas as what to check next!???
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You could do a full compression test first (get the readings and let us know what the pistons said) , then carefully take off the cam chains & take apart the valve head.
if i read correctly? you said it skipped the cams ? – So i suspect (guessing) that there is 1 valve that was hit by the piston , even just a smidge , if the valve has, it will show itself when you remove the valve heads off the bike.  Tedious process but its the only way to be sure. You can also do leak-down tests (plenty videos on youtube, sorry i couldn’t make a tutorial on the forum just yet)
If we can be sure the whole engine is 100% checked over and you put new head gaskets on , then we move up to the electric side of things but we cross this bridge until the engine is verified first.   Valve Clearances do help also.
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Yeah thats what had happened before I got the bike it had skipped timing and the pistons had smashed the valves. I ended up replacing pretty much the whole front motor. But I dont have any tools at the moment so ill have to find some but ill let you know what the readings say after I do it. Idk how long thats gunna take tho.
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Alright I got the results and I dont think im going to be hearing any good news from this but the rear compression is at 125psi and the front compression is 60-65 psi i did this with a cold motor but I dont think the results would change much if it was warm but i could be wrong if I am let me know and ill rerun test with a warm motor! So let’s hear what’s the next steps are.
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Alright here’s an update I got everything stripped down but I didn’t open it up yet it got dark and im doing this outside rather not deal with the mosquitoes there bad out here and if it another wet morning like yesturday then I’d rather have the motor all closed up until that dew passes threw. But I stripped her down today so tomarrow I can open up and see what’s wrong. And I had just redone the valves and replaced the cam cuz it was snapped whenni first opened her up thats how I had got it. the timing only had skipped 2 maybe 3 links at the most! I shale see the damage in the morning and ill update then thanks!
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Could be pistons/piston rings or valve seats themselves as long as you are certain the valves are 100% straight.
Put a new metal gasket again just incase.  (Compression loss due to head-gasket failure can happen , just like cars)
The site’s image uploader seems to have bugs i am sorting soon, so in the interim, use this website to upload images below:
https://postimg.ccThen just copy & paste forum links that start withÂ
"[Â I M G ...........]"Â , this forum will translate them in to live images.Sorry for the hopping around , I will fix the site’s uploader.
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I was thinking of just putting in new piston and rings, new cylinder, new cam chain tensioner cuz the one I already replaced is broke. I’m just trying to figure out if I have an old or new style cylinder! I’m thinking its an old one but it says it could be a new one cuz its newer then 2007. I dont have a dial caliper thanks to my ex taking all my tools. So I might have to go pick one up to find out what cylinder I need!
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If my timing was not 100 percent could that be a reason the compression could be off. I dont have the funds to get the parts I want I was thinking about putting it back together and making sure timing cuz I relized I had my timing at 14 links and as I was reading through forums it said it should be 16 could that be why compression is down.
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14 down from 16 would throw timings off yes and likely as Simon was saying that you may have hit something inside the engine, as there is a very small margin between the piston and the valves.
Like he also said, put some petrol or some liquid through the valves and see if they leak through without you pressing them down, it could be better than just visually looking at them. I would mention a likely hood of needing to replace the valve seals (if i didn’t say it before)
Rebuilding the front engine is a good idea to put fresh life in to the bike again.
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Yeah i did put some gas down on the valves they are good thank fully. I guess it was unavoidable that front motor needs to be rebuilt when i got the bike. So thats what im going to do. Im just hoping that
Hyosung Cylinder Front with Adjuster and Gasket (new model) GV250
This is the correct part and that when it says afjustet it is talking about the cam chain tensioner. Im assuming
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- You cannot reply to this topic.
- This topic has 15 replies, 3 voices, and was last updated 11 months ago by .
-
Posts
-
-
Okay so I was riding down the freeway doing 85 all of a sudden I lost power bike won’t go over 35 I was 2 exits away from where I was going so I threw on my hazards. I checked hoses those seem to be good I did notice I lost a cam chain tensioner nut the middle one.my cam chain was loose and and It had skipped a couple links so I ended up getting the motor back to how it should be thinking that would fix the problem it did however get ride of the ticking noise but I still can’t get the bike over 30 any ideas as what to check next!???
-
-
You could do a full compression test first (get the readings and let us know what the pistons said) , then carefully take off the cam chains & take apart the valve head.
if i read correctly? you said it skipped the cams ? – So i suspect (guessing) that there is 1 valve that was hit by the piston , even just a smidge , if the valve has, it will show itself when you remove the valve heads off the bike.  Tedious process but its the only way to be sure. You can also do leak-down tests (plenty videos on youtube, sorry i couldn’t make a tutorial on the forum just yet)
If we can be sure the whole engine is 100% checked over and you put new head gaskets on , then we move up to the electric side of things but we cross this bridge until the engine is verified first.   Valve Clearances do help also.
-
Yeah thats what had happened before I got the bike it had skipped timing and the pistons had smashed the valves. I ended up replacing pretty much the whole front motor. But I dont have any tools at the moment so ill have to find some but ill let you know what the readings say after I do it. Idk how long thats gunna take tho.
-
-
Alright I got the results and I dont think im going to be hearing any good news from this but the rear compression is at 125psi and the front compression is 60-65 psi i did this with a cold motor but I dont think the results would change much if it was warm but i could be wrong if I am let me know and ill rerun test with a warm motor! So let’s hear what’s the next steps are.
-
-
-
-
Alright here’s an update I got everything stripped down but I didn’t open it up yet it got dark and im doing this outside rather not deal with the mosquitoes there bad out here and if it another wet morning like yesturday then I’d rather have the motor all closed up until that dew passes threw. But I stripped her down today so tomarrow I can open up and see what’s wrong. And I had just redone the valves and replaced the cam cuz it was snapped whenni first opened her up thats how I had got it. the timing only had skipped 2 maybe 3 links at the most! I shale see the damage in the morning and ill update then thanks!
-
-
Could be pistons/piston rings or valve seats themselves as long as you are certain the valves are 100% straight.
Put a new metal gasket again just incase.  (Compression loss due to head-gasket failure can happen , just like cars)
The site’s image uploader seems to have bugs i am sorting soon, so in the interim, use this website to upload images below:
https://postimg.ccThen just copy & paste forum links that start withÂ
"[Â I M G ...........]"Â , this forum will translate them in to live images.Sorry for the hopping around , I will fix the site’s uploader.
-
I was thinking of just putting in new piston and rings, new cylinder, new cam chain tensioner cuz the one I already replaced is broke. I’m just trying to figure out if I have an old or new style cylinder! I’m thinking its an old one but it says it could be a new one cuz its newer then 2007. I dont have a dial caliper thanks to my ex taking all my tools. So I might have to go pick one up to find out what cylinder I need!
-
If my timing was not 100 percent could that be a reason the compression could be off. I dont have the funds to get the parts I want I was thinking about putting it back together and making sure timing cuz I relized I had my timing at 14 links and as I was reading through forums it said it should be 16 could that be why compression is down.
-
14 down from 16 would throw timings off yes and likely as Simon was saying that you may have hit something inside the engine, as there is a very small margin between the piston and the valves.
Like he also said, put some petrol or some liquid through the valves and see if they leak through without you pressing them down, it could be better than just visually looking at them. I would mention a likely hood of needing to replace the valve seals (if i didn’t say it before)
Rebuilding the front engine is a good idea to put fresh life in to the bike again.
-
Yeah i did put some gas down on the valves they are good thank fully. I guess it was unavoidable that front motor needs to be rebuilt when i got the bike. So thats what im going to do. Im just hoping that
Hyosung Cylinder Front with Adjuster and Gasket (new model) GV250
This is the correct part and that when it says afjustet it is talking about the cam chain tensioner. Im assuming
-
- You cannot reply to this topic.