Cylinder head

I recently had my motor seize up on me while riding dunes. I haven't taken a close look at the cylinder due to not getting it off yet but I did get the head off. How do I know if I need a new head/get it milled to fix? This bike is a 1998 CR250R

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Looks like there are some deep Scratches or chips... If that is the case those areas will absorb the heat and cause issues. I could be wrong but I think the head is expensive from Honda. You might just be better off with a new head. The other option would be smoothing everything out and cleaning by ultrasonic or another method. And by Honda I mean oem parts from rockymoutianatvmc, or eBay or the website of your choice! I personally like servicehonda.com also.

what the &%$#@! do you guys do to your bikes ? not maintain them at all ? just because it isn't a 4 stroke, doesn't mean it doesn't need maintenance done. there are 3 heads in a row on this site that resembles this now.

If that's the case, I will probably just get one from Phatheads racing since I'm turning my bike into a dune machine. And it's not that I don't keep up in maintenance but I think I was running lean. I was climbing sand mountain and it just seized. No idea what happened

what the &%$#@! do you guys do to your bikes ? not maintain them at all ? just because it isn't a 4 stroke, doesn't mean it doesn't need maintenance done. there are 3 heads in a row on this site that resembles this now.

The guy I bought my bike off didn't maintain it. Have a look at this... Its all good now.

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i bought one one eBay recently for like $25 shipped. Do that. Make sure its clean.

 

I surfaced it by wetting sand paper on a granite table top (sand paper sticks) and moving the head flat on it. Did it up to 600 grit to make it sparkly clean.

 

i would like to see the jug when you take it off if you don't mind posting ; |

If I have time to take it off sometime soon then I'll definitely posted a pic on here.

You have to err on the rich side in dunes, now she's " all blowed up " :naughty:

 

What kind of 2 smoke oil were you using, what ratio do you mix at ?

 

I think I was running lean. I was climbing sand mountain and it just seized. No idea what happened

You have to err on the rich side in dunes, now she's " all blowed up " :naughty:

What kind of 2 smoke oil were you using, what ratio do you mix at ?

Yamalube at 32:1

real dune machines dont run on pump gas. get c12 and mix it heavy with 927 or klotz

real dune machines dont run on pump gas. get c12 and mix it heavy with 927 or klotz

Not a true dune machine. Take it out there once a year, maybe twice. Since it seized I'm gonna big bore it and go straight duning. How heavy would you recommend mixing at? I used to have it at 20:1 but since rejected for 32:1

That head looks like something came apart. Maybe rod bearing?

That head looks like something came apart. Maybe rod bearing?

The electrode on the spark plug was smashed against the threads so I assume a bearing went on on the rod or wrist pin. Also some of the piston skirt shredded off

Edited by freelove33

 why use the crappiest gas you can ?  riding once or twice a year you should be able to afford a 5gal jug of c12. 20:1 will be fine but i wouldnt do it with yamalube.

I'm going to try the same vegetable oil that Mcdonalds uses for their Fries. Not sure if it's going to equal Castor. Maxima uses a very robust additive package in their synthetic oils, so Maxima K2. Their Castor is so good, it doesn't need a robust additive package.

 

 

i wouldnt do it with yamalube.

harryhandshake doesn't use 2 cycle oil when he mixes his gas. He either uses brake fluid or Type F transmission fluid :thumbsup:

 

 why use the crappiest gas you can ?

I don't ride twice a year. Only dunes twice a year. I try to trail ride about every weekend. But I've always used yamalube, never had a problem. But once I rebuild I'll make sure I take extra good care :ride:

thats gonna be one sorry ass dune machine if it doubles as a trail bike on other weekends. generally i hit them dunes couple times a year. ill try not to roost ya to bad :smirk:

Edited by harryhandshake

thats gonna be one sorry ass dune machine if it doubles as a trail bike on other weekends. generally i hit them dunes couple times a year. ill try not to roost ya to bad :smirk:

Well I never had anyone to go to te dunes with but now a couple of my friends who happen to be hardcore dune riders somehow managed to get their hands on new machines. We'll see how it goes. I'll be cutting way back on trails and go to the dunes a lot more now.

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