07 CR250 cylinder/piston help

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1/22/2018 8:42 AM

I’m looking for some thoughts and opinions on what is causing this? The piston has the same striations directly behind the fronts. It’s directly in the front and back. The back striations are right over the ring pin. There is 30 hours of trail riding on this piston and cylinder since being replaced and honed.
The piston that was removed from the bike was in it when the bike was purchased and was in extremely bad condition. It had the same problem but I assumed it was because of the piston condition.
Photo

Photo

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1/22/2018 9:16 AM

Ok I see a couple of things and will offer some advice.
1. I don't see any cooling holes in the piston for the exhaust bridge and that is causing the bridge to swell and cause the marks on the piston in the photo.
2. I see a lot of wear on the piston skirt. Looks to be from cylinder ports sharp from wear.
3.I see a good bit of blow by from the rings leaking combustion gasses.

Things to do:
1. have cylinder checked for wear. Then replate as needed.
2. Don't run 30 hours on a single ring set up as that is too long and creates excess blow by at the rings and excess piston wear.
3. Drill needed cooling holes in the piston below the rings to match the exhaust port bridge.

Paw Paw

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1/22/2018 9:53 AM

Paw Paw 271 wrote:

Ok I see a couple of things and will offer some advice.
1. I don't see any cooling holes in the piston for the exhaust bridge and that is causing the bridge to swell and cause the marks on the piston in the photo.
2. I see a lot of wear on the piston skirt. Looks to be from cylinder ports sharp from wear.
3.I see a good bit of blow by from the rings leaking combustion gasses.

Things to do:
1. have cylinder checked for wear. Then replate as needed.
2. Don't run 30 hours on a single ring set up as that is too long and creates excess blow by at the rings and excess piston wear.
3. Drill needed cooling holes in the piston below the rings to match the exhaust port bridge.

Paw Paw

Thanks for the advice. When I did the rebuild I took my cylinder to our local shop and told them to inspect it and do whatever it needs then measure and order a piston. They just honed and gave it back. I’m not a expert with this stuff but it didn’t look good to me which is why I took it to them.

I had a 2004 CR before this 07 and used it for the same riding. I had it since new and would replace the piston about every 15-20 hours but they were always in great condition. I felt like I was throwing out good pistons. I
started to leave the piston in for the riding season (warm spring until colder temps only riding Sunday’s) and they would still look good. Going off the advice from fellow riders I never drilled the lubrication and never had an issue like this.

I’m going to take your advice on this one to see if I get better results. I’m also going to take my cylinder to a different shop.

Thanks

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1/22/2018 10:12 AM

Buy a wiseco piston & send it and your cylinder to millennium tech. Top quality guys

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

1/22/2018 11:03 AM

Acidreamer wrote:

Buy a wiseco piston & send it and your cylinder to millennium tech. Top quality guys

Agree and ask them to drill the holes in the piston.

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The older I get, the faster I was.

1/22/2018 11:04 AM

Paw Paw, do you recommend drilling a stock piston? They come out of the factory without holes.

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The older I get, the faster I was.

1/22/2018 11:19 AM

No need to drill holes in a piston on a cr250 from 07.. Get a vertex piston and don't go over the 20hours. I change it with 15 hours of riding on my 07. Never had any problems. Get some good oil(motul-denicoll-xr77) mix it 40:1. Make sure the cylinder is round and not ovale.

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1/22/2018 11:20 AM

Acidreamer wrote:

Buy a wiseco piston & send it and your cylinder to millennium tech. Top quality guys

I’ve been hearing that name a lot lately, Millennium Tech. Not that I’m asking you for a exact price but do you have any idea of what they charge or their turnaround time?

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1/22/2018 11:24 AM
Edited Date/Time: 1/22/2018 11:27 AM

Looks like a lot of dirt in there. The airbox seal is prone to leak. Vertical marks all the way around says dirt got in somewhere. I use a wossner twin ring piston for extra stability and life.

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1/22/2018 11:26 AM

Acidreamer wrote:

Buy a wiseco piston & send it and your cylinder to millennium tech. Top quality guys

(C)oal(R)egion250 wrote:

I’ve been hearing that name a lot lately, Millennium Tech. Not that I’m asking you for a exact price but do you have any idea of what they charge or their turnaround time?

I want to say like $250 for it to be done. If you do a core exhange youll have a brand new cylinder in a week. If not it depends on their workload. Longest ive ever waited was 3 weeks.

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

1/22/2018 11:34 AM

r18b wrote:

No need to drill holes in a piston on a cr250 from 07.. Get a vertex piston and don't go over the 20hours. I change it with 15 hours of riding on my 07. Never had any problems. Get some good oil(motul-denicoll-xr77) mix it 40:1. Make sure the cylinder is round and not ovale.

I’m starting to get worried that the cylinder is oval. When I found this bike it was in great condition, I let my excitement get the best of me. The engine doesn’t match the rest of the bike because it was in rough condition. It’s like the engine is ten years older than the bike and they didn’t take care of it but they did with everything else. I still don’t understand it but anyway.... I run a wiseco and mix Amsoil 50:1 to 105 octane fuel. I just pulled this piston last night and it was very well lubricated, more than what I usually see with other bikes I had. That is making believe that I do have a cylinder issue.
This is why I don’t drill the holes because for every person that says to do it there is another saying no.

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1/22/2018 11:59 AM

The use of oil looks bad.. it's looks even worst then i had with valvoline in the past. I change it to motul then to denicoll and now i'm using castrol xr77. All three are the right choice and don't leave that amount of oil what you now have on ur piston. A slightly oval cylinder is not a problem but instead of replating for 250 get a new oem for 310. Nothing beats oem.

Vertex is the best piston.. give it a try. Together with one of those above 3 oils and mix it 40:1. Make sure ya have the right main jet coz with denicol ya can't see any colour on a sparkplug lol

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1/22/2018 12:34 PM

r18b wrote:

The use of oil looks bad.. it's looks even worst then i had with valvoline in the past. I change it to motul then to denicoll and now i'm using castrol xr77. All three are the right choice and don't leave that amount of oil what you now have on ur piston. A slightly oval cylinder is not a problem but instead of replating for 250 get a new oem for 310. Nothing beats oem.

Vertex is the best piston.. give it a try. Together with one of those above 3 oils and mix it 40:1. Make sure ya have the right main jet coz with denicol ya can't see any colour on a sparkplug lol

I have a Lectron Carb that seems to do a pretty good job. On warmer days or when riding a bit harder I just have to open the power jet slightly but I’ll give try.

If you’re saying a new cylinder is 310, where is that from?

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1/22/2018 12:40 PM

Hondas4Life3 wrote:

Looks like a lot of dirt in there. The airbox seal is prone to leak. Vertical marks all the way around says dirt got in somewhere. I use a wossner twin ring piston for extra stability and life.

I didn’t really notice the vertical marks. It’s easier to see them in the picture because of the flash. I have the TX race restyle kit on my bike. It looks cool but is a pain in the ass. It leaves the air box wide open on the throttle side because the number plate doesn’t go into it like OEM would. I thought I had it under control but maybe I don’t. Still doesn’t really explain dirt getting past the filter.

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1/22/2018 12:58 PM

r18b wrote:

The use of oil looks bad.. it's looks even worst then i had with valvoline in the past. I change it to motul then to denicoll and now i'm using castrol xr77. All three are the right choice and don't leave that amount of oil what you now have on ur piston. A slightly oval cylinder is not a problem but instead of replating for 250 get a new oem for 310. Nothing beats oem.

Vertex is the best piston.. give it a try. Together with one of those above 3 oils and mix it 40:1. Make sure ya have the right main jet coz with denicol ya can't see any colour on a sparkplug lol

(C)oal(R)egion250 wrote:

I have a Lectron Carb that seems to do a pretty good job. On warmer days or when riding a bit harder I just have to open the power jet slightly but I’ll give try.

If you’re saying a new cylinder is 310, where is that from?

Partzilla has it for 05-07 for 309 dollar new oem honda cr250 cylinder. imagine that such a cylinder in europe cost 870 euro lol

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1/22/2018 2:17 PM

R18b: that’s rough haha.

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1/22/2018 3:45 PM
Edited Date/Time: 1/22/2018 3:50 PM

(C)oal(R)egion250 wrote:

I didn’t really notice the vertical marks. It’s easier to see them in the picture because of the flash. I have the TX race restyle kit on my bike. It looks cool but is a pain in the ass. It leaves the air box wide open on the throttle side because the number plate doesn’t go into it like OEM would. I thought I had it under control but maybe I don’t. Still doesn’t really explain dirt getting past the filter.

Its the actual air boot seal into the airbox. There is a foam gasket that will degrade over time and leak allowing dirt to get in after where the air filter is mounted. The air boot and plastic housing bolt together with a seal in-between.

Check this out. I use one https://www.ebay.com/itm/CR250-07-AIR-BOX-SEAL-KIT-2002-2007-CR250R-SEALING-RINGS-CR-250-AIR-BOX-FIX-KIT/253352427278?hash=item3afcfb3f0e:m:mOyqywZM6Xtav3gRwfbSffA

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1/22/2018 5:15 PM

Hondas4Life3 wrote:

Its the actual air boot seal into the airbox. There is a foam gasket that will degrade over time and leak allowing dirt to get in after where the air filter is mounted. The air boot and plastic housing bolt together with a seal in-between.

Check this out. I use one https://www.ebay.com/itm/CR250-07-AIR-BOX-SEAL-KIT-2002-2007-CR250R-SEALING-RINGS-CR-250-AIR-BOX-FIX-KIT/253352427278?hash=item3afcfb3f0e:m:mOyqywZM6Xtav3gRwfbSffA

I would always grease that gasket with dialectric whenever I took my ‘02 125 apart. I hated the carb on that bike; would always bog down low and spent far too long chasing jetting for it to foul plugs or run like crap.

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If you're not mixing gas, you're not haulin ass.

1/22/2018 5:38 PM

r18b wrote:

Partzilla has it for 05-07 for 309 dollar new oem honda cr250 cylinder. imagine that such a cylinder in europe cost 870 euro lol

Lots of people are saying it's a national back order and has been for a few months.

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The older I get, the faster I was.

1/22/2018 7:41 PM
Edited Date/Time: 1/22/2018 7:51 PM

Get a new cylinder and new piston and start over. And quit letting shops hone the cylinder.

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1/22/2018 10:09 PM

(C)oal(R)egion250 wrote:

I have a Lectron Carb that seems to do a pretty good job. On warmer days or when riding a bit harder I just have to open the power jet slightly but I’ll give try.

If you’re saying a new cylinder is 310, where is that from?

r18b wrote:

Partzilla has it for 05-07 for 309 dollar new oem honda cr250 cylinder. imagine that such a cylinder in europe cost 870 euro lol

captmoto wrote:

Lots of people are saying it's a national back order and has been for a few months.

I'm going to order a new oem cylinder in the UK. Waiting time is 4 weeks price is 290 pounds and has to come from honda europe(got a mail from them about the delivery time for a cylinder). In Holland it cost 870 euro and it has to come from honda europe.

So i don't think it takes a few months . Motorsports has it in stock. Partzilla he can ask thats the cheapest one.

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1/22/2018 10:15 PM

Rockinar wrote:

Get a new cylinder and new piston and start over. And quit letting shops hone the cylinder.

Thumbs up for a fresh start.

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1/22/2018 11:52 PM

r18b wrote:

I'm going to order a new oem cylinder in the UK. Waiting time is 4 weeks price is 290 pounds and has to come from honda europe(got a mail from them about the delivery time for a cylinder). In Holland it cost 870 euro and it has to come from honda europe.

So i don't think it takes a few months . Motorsports has it in stock. Partzilla he can ask thats the cheapest one.

Check EBay. I'm almost positive Honda of Troy had only like 3 weeks ago.

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1/23/2018 4:07 AM

captmoto wrote:

Lots of people are saying it's a national back order and has been for a few months.

r18b wrote:

I'm going to order a new oem cylinder in the UK. Waiting time is 4 weeks price is 290 pounds and has to come from honda europe(got a mail from them about the delivery time for a cylinder). In Holland it cost 870 euro and it has to come from honda europe.

So i don't think it takes a few months . Motorsports has it in stock. Partzilla he can ask thats the cheapest one.

Rockinar wrote:

Check EBay. I'm almost positive Honda of Troy had only like 3 weeks ago.

checking ebay every day.. So far only a 02-04 cylinder and even that one was way overpriced. For me it's useless to get a new one from the usa..
Have to pay to much tax in Holland over a cylinder what i buy in the USA. So the Uk is my way to go. Every car or motorcylce part we must pay taxes if we get it from outside europe. That's around a 25 dollar on a 100 dollar. In the end a cylinder from the USA cost me around 60 euro more then a cylinder ordered in the UK. Shit taxes lol

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1/23/2018 7:48 AM
Edited Date/Time: 1/23/2018 2:19 PM

The fine vertical scratches on the piston are dirt/sand getting past the filter.
Things to watch for:
If you're using the stock 07 airbox, there are plastic nubs which protrude into the filter mounting plate where the filter sits flat against the airbox. The nubs interfere with the filter mounting and can allow dirt to get past if the filter is not greased where it sits against the airbox. Try installing the empty filter frame (filter removed) onto the airbox and install the wing nut. Observe the perimeter of the filter frame and observe that the filter frame does not sit fully down flat onto the airbox mount even with the wing nut tightened. To fix this, you can purchase an aftermarket filter mounting plate, or use a 2001 and earlier stock CR250 metal mounting plate. You'll need to drill out the nubs, but the older CR250 plate bolts align perfectly with removed nubs. You'll also need a plastic 2001 and earlier filter frame if you go this route.

Also, there is a foam gasket between the airboot and the outside of the airbox where the airboot mounts on. The foam degrades over time then and allows dirt to get past. Replace when you are installing the new mounting plate.

Also, if you are using an air filter that has a rubber grommet underneath the wing nut, be careful not to over tighten the wing nut. This can cause the rubber seal to flex and allow dirt to get past between the grommet and the filter. To solve this, we use gasoline resistant Seal All to glue the foam to the rubber grommet. Start with a perfectly clean and dry air filter with no oil on it and allow the Seal All to dry overnight. Silicone will decompose in this environment, do not use silicone.

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1/23/2018 8:23 AM

Rockinar wrote:

Get a new cylinder and new piston and start over. And quit letting shops hone the cylinder.

r18b wrote:

Thumbs up for a fresh start.

That’s what I’m going to do. It’s really sucks because it ruins plans I had for other stuff but if there is one thing I hate to cheap out on, it’s my bike. Wish I would have caught it sooner. When I pulled the piston out that came with the bike it was the same way. I didn’t think much of it because the piston was shot. The skirt was literally starting to come apart. I wish the boneheads at the shop would have caught onto it for me.

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1/23/2018 8:26 AM

40 wrote:

The fine vertical scratches on the piston are dirt/sand getting past the filter.
Things to watch for:
If you're using the stock 07 airbox, there are plastic nubs which protrude into the filter mounting plate where the filter sits flat against the airbox. The nubs interfere with the filter mounting and can allow dirt to get past if the filter is not greased where it sits against the airbox. Try installing the empty filter frame (filter removed) onto the airbox and install the wing nut. Observe the perimeter of the filter frame and observe that the filter frame does not sit fully down flat onto the airbox mount even with the wing nut tightened. To fix this, you can purchase an aftermarket filter mounting plate, or use a 2001 and earlier stock CR250 metal mounting plate. You'll need to drill out the nubs, but the older CR250 plate bolts align perfectly with removed nubs. You'll also need a plastic 2001 and earlier filter frame if you go this route.

Also, there is a foam gasket between the airboot and the outside of the airbox where the airboot mounts on. The foam degrades over time then and allows dirt to get past. Replace when you are installing the new mounting plate.

Also, if you are using an air filter that has a rubber grommet underneath the wing nut, be careful not to over tighten the wing nut. This can cause the rubber seal to flex and allow dirt to get past between the grommet and the filter. To solve this, we use gasoline resistant Seal All to glue the foam to the rubber grommet. Start with a perfectly clean and dry air filter with no oil on it and allow the Seal All to dry overnight. Silicone will decompose in this environment, do not use silicone.

What are your thoughts on that MXbones aur filter seal kit or the twin air power flow kit?

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1/23/2018 11:31 AM

Rockinar wrote:

Get a new cylinder and new piston and start over. And quit letting shops hone the cylinder.

r18b wrote:

Thumbs up for a fresh start.

(C)oal(R)egion250 wrote:

That’s what I’m going to do. It’s really sucks because it ruins plans I had for other stuff but if there is one thing I hate to cheap out on, it’s my bike. Wish I would have caught it sooner. When I pulled the piston out that came with the bike it was the same way. I didn’t think much of it because the piston was shot. The skirt was literally starting to come apart. I wish the boneheads at the shop would have caught onto it for me.

new cylinder..get a vertex piston (the only good thing about a ktm is the vertex piston and magura clutch.. i use them both lol)
get some good oil for the mix and bring back the smile on the red.

Twin air power flow kit i have it on the cr85 not on the cr250.. take the airbox apart, clean it and put some fresh silicone sealant between it. Job done

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1/23/2018 2:15 PM

(C)oal(R)egion250 wrote:

What are your thoughts on that MXbones aur filter seal kit or the twin air power flow kit?

Either one is a tremendous improvement over the stock Honda setup. We'd probably go with the MX Bonz kit since its less expensive. Use the money you saved from not buying the Twin Air kit to buy new tires, or chain, or clutch plates, or you get the idea.....

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1/23/2018 3:58 PM

(C)oal(R)egion250 wrote:

I have a Lectron Carb that seems to do a pretty good job. On warmer days or when riding a bit harder I just have to open the power jet slightly but I’ll give try.

If you’re saying a new cylinder is 310, where is that from?

r18b wrote:

Partzilla has it for 05-07 for 309 dollar new oem honda cr250 cylinder. imagine that such a cylinder in europe cost 870 euro lol

captmoto wrote:

Lots of people are saying it's a national back order and has been for a few months.

Called them today and that’s what I was told, on back order from Honda. They don’t have any idea of when it’ll be in.

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