Barrel spacers?

  • Hi all I’m new here hence not being able to find the parts i need on the internet anywhere so i was wondering if anyone knew where i can get hold of some barrel/cylinder spacers? Ive recently had the head skimmed on my DT125RE and when i fired her back up after she was put back together the piston was hitting the head cover! I need some spacers to counter this! Or any other suggestions are welcomed! Thanks

  • @LucasHutch Wow? How much did they skim it by.

    The common convention is double up on base gaskets. In your case, sounds like you will need three! That doesn't sound right though.

    Shifting the barrel upwards will affect the port timings.

    From experience, on the DTRE ignition, even 1mm increase in port timings adversely affects the performance.

    Basically, you're shifting peak power towards the higher end of the RPM range, where the DTRE igntion starts to retard.

    Instead, I'd go with a thicker head gasket.

    Could try using that, or doubling up on that. Copper Head Gaskets are reusable.

    But make sure you know what you're doing.

    I've never skimmed the head so much that it fouled the piston.

    The other alternative is to modify the piston and shave some of the top off. This would weaken the piston.

    • Double/Triple up Base Gasket
      ** Note this can adversely affect the performance
    • Use a flat copper head gasket of higher thickness
    • Shave the piston crown so it no longer fouls

    In any situation, remember heat expands, so as it heats up, it may still hit the head and that at speed would be disasterous!

  • @LucasHutch I agree with calum. Barrel spacers would change the port timing but they are on eBay if you do want them. I would post a link but I don't know how to but if you search eBay for 'yamaha dt125r barrel spacers you will find them in various thickness.

  • eBay item number:
    Copper gasket that is 0.55mm, it’s twice as thick as the other I think...

  • i would advise throwing that head in the scrap and get a high compression replacement tzr 4dl use same heads as dts use a high compression off 1 of those standard if piston is hitting the head than its plian and simple useless will search the head reference up to post 2rh tzrs range y1 to y4 y1 best compression cant say on dts/4dls if u use thicker head gasket u r undoing the skimming any ways as u r spacing out the combustion chamber which the skimming is done to reduce thus upping compression

  • ok seems dts use the same compression code as 2rh tzrs y1 is the best compression
    y4 is the lowest check yours is y1 if its not then try to replace with a y1and only skim it if warped just to flatten not any further or your back to square 1 hope this info helps

    if u look under the sparkplug hole u will see stamped y1 thats top compression head

  • Hi all thanks for all the advice it’s really helpful! Yeah he had to skim a lot off because it looks like someone Had prized off the head before with a screwdriver or something and made a big gouge in it! I’ve ordered the copper gasket (budget reasons 🤣) so I’ll try that and see how she goes but if not I’ll give a new head a go. I’ll post an update soon

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