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New 700cc Outfit

Discussion in 'The Lounge' started by Signal, Aug 26, 2018.

  1. halfmile

    halfmile XS Builder Top Contributor XS650.com Supporter

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    kansas
    IMHO there are only 2 actual builders on this site. You and rehar. The rest (myself included) fall between restoration, modification, and re assemblers. You set the bar so high all I can do is look up with envy. You are a "complete builder" and your work is simply MAGNIFICENT!!:thumbsup::thumbsup::thumbsup::thumbsup::thumbsup::thumbsup:
     
  2. YamadudeXS650C

    YamadudeXS650C Central New York XS650 Top Contributor XS650.com Supporter

    I feel a special privilege having the opportunity to be witness to this amazing build. I'm in awe.
    Thank you for sharing.
     
    MaxPete and TwoManyXS1Bs like this.
  3. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Probably too late for this, at this stage of your build.

    Any provisions for cooling the engine case?
     
    MaxPete likes this.
  4. B_Crabaugh

    B_Crabaugh XS650 Addict

    This is absolutely insane!!!
     
    MaxPete and YamadudeXS650C like this.
  5. FLEA

    FLEA XS650 Junkie

    please hurry up and finish this ... your killing us with the suspence .. its an amazing job and should be a hell of a weapon
     
    MaxPete likes this.
  6. Signal

    Signal XS650 Junkie Top Contributor

    Thanks for the interest, encouragement and positive comments guys.

    Flea we are going flat out to get this ready for the new season no one wants to hear this run more than us and I hope you are right and it is a weapon.
    We have heard that the MPSC race meeting in Timaru early December has 20 sidecars entered we want to take the XS and the RD to that.

    TwoMany heat soak was a problem with the 700 built back in the 70’s and I think it will be a problem for us as well. We intend to wrap the headers and use some form of heat shield to stop the pipes heating the cases.

    On a Bucket tuning forum that I lurk on they had some success using a deflector plate below the barrels to stop the heat radiating onto the cases.

    In our favour we race in the classic class and the races are all short. We hope if they don’t muck about on the start grid we should still be making reasonable power at the end of the race.

    Meanwhile work progresses

    The platform plywood has been cut, just need to check the cut-out for the rider’s foot is big enough before covering it.
    2019_0819RD700000comp.jpg

    The mufflers have been finished and buffed and the brackets for mounting the chambers are finished.

    Mounts for the EGT thermocouples have been added. I believe ideally they should be 150mm from the piston however we have had to compromise on this. Our temperatures will be even more specific to our motor.
    2019_0819RD7000007comp.jpg 2019_0819RD7000008 comp.jpg

    The fuel manifold is just about finished just need to positon the return outlet. I have left one end open for now to get the swarf out when the return spigot is drilled.

    I Lumiwelded this together it is the first time I have used this product. It’s just like soldering and although I made a bit of a hash of it at first, after a while it became easy to get a reasonable job. It is very easy to melt your work though! The only drawback with Lumiweld is the price.

    Once the pipes are made I can carry on porting the cylinders while my mate makes the fuel tank.

    The pistons have been sanded and polished to remove stress risers and can be set away for ceramic coating.

    After they are done we will be ready to check clearances etc. and put the motor together.

    The throttle cables are mostly made and the pull is pretty hard. It may be cable routing but if not we may need to move away from the quick pull throttle.
    2019_0819RD7000006comp.jpg

    2019_0819RD7000004 comp.jpg

    A mould for the side guard has been made; it’s pretty rough but will be good enough. The corners and other rounded parts are made with potter’s clay then the glass is laid on to it before it dries out. It’s a quick way to get a shape but the downside is more prep work is required before painting

    We have had a lot of visitors to the workshop lately with interested growing and people dropping in but today was a bit of a record we had 8 visitors throughout the day.


    While all this has been going on a mate of ours has been building an XS powered unit, it is his first attempt and he has made a very good job of it so far. It will be neck and neck to see who the first running is.

    He has a very small budget and is very ingenious in reusing random stuff, his latest exploit is a muffler canister made from a fire extinguisher body.
    Below is a picture of his rolling chassis. malcoms.jpg
     
  7. Mailman

    Mailman Hardly a Guru Top Contributor

    You guys really are in a class by yourself......good stuff!
    :popcorn:
     
    gggGary and Jim like this.
  8. MaxPete

    MaxPete Life with Lucille...I suggest, she decides. Top Contributor XS650.com Supporter

    WOW!

    Not suggesting you complicate things more than necessary, but what about a couple of electric cooling fans pointed at the heads & barrels? That big front wheel really blocks the airflow I’d guess and the fans might help to keep things under control and make running more steady.

    On the throttle cable issue - how about a throttle shaft ala Honda CB750 to pull up on the slides? The might make the pull easier and still allow for individual tuning of the carbs.
    upload_2019-8-18_12-19-28.jpeg
     
    YamadudeXS650C, Signal and Jim like this.
  9. Signal

    Signal XS650 Junkie Top Contributor

    Max Pete with regard to the throttle pull I think the rider should just harden up. Actually with a grip on the bar it probably won’t be that bad.

    The pistons are back home from with their new ceramic tops and slippery sides.
    2019_0908RD7000004 comp.jpg

    The main fuel tank is finished just need to make a breather restrictor thingy. This tank is 8 litres brimming, we plan to have another 5L tank below the outside kneeler trough giving us 13 litres in total, and just about ok for petrol but no good if we go the methanol route.

    The chain was also running too close to one of the frame tubes so the rear sprocket needed to move over so the rear hub had to come apart and have a bit taken off it.
    2019_0908RD7000001 comp.jpg


    Finally finished bringing the Rajoot barrels up to scratch it has been a time consuming process. The inlet, boost, exhaust and transfer ports have been done. There was a lot of metal to move as the transfers were very low. On the plus side the quality of the casting is better than the original Japanese ones and the transfer port divider is straight.

    I bought a mini right angle die grinder to do the job and it worked very well, after the ports were repositioned they were sanded and the edges were chamfered as a final touch the bores were masked up and the ports were bead blasted except for the exhaust which was given a quick polish. I didn’t go nuts on the polishing as it is going to be reprofiled once we get the thing running reliably.

    A standard Rajoot barrel (left) next to the modified (right).

    2019_0908RD7000010 comp.jpg 2019_0908RD7000011 comp.jpg
    2019_0908RD7000016 comp.jpg 2019_0908RD7000017 comp.jpg

    As the porting stands now it is to Dale Alexander’s specs with the exception of the exhaust port which is at 28mm. With this setup the blow down is 32 degrees when the exhaust is raised later the blowdown duration will be 34 degrees. A stock RD has 35 degrees blowdown. It will be interesting to see the effect on power delivery.

    Also found that the clearance holes for the cylinder bolts were not deep enough, it is easy enough to drill them 5mm deeper but two of them come very close to the auxiliary transfer ports, luckily no daylight shone through.

    Have just about finished dowelling the heads to the barrels; this is to ensure the squish band is central to the cylinder/piston.

    2019_0908RD7000022 comp.jpg

    A start has been made on the seat unit which needs to be made before the passenger grab handles can be made. We are using the quick and dirty way with a rough mould which means more clean-up of the final product is required. The fronts of the kneeler troughs were made by glassing over a plastic ball that was inflated to the required size.

    As there are likely only two at the most being made it is an acceptable trade off.
    The mould covered in parcel tape before glassing.
    2019_0908RD7000005 comp.jpg
    The mould after the seat was taken out. It came out pretty easily with the help of some compressed air. The area where the tape has lifted is where the compressed air got under the tape.
    2019_0908RD7000008 comp.jpg

    This is just a start and in the photo it is not even sitting properly on the bike it was just plonked on after it came from the mould untrimmed.
    2019_0908RD7000007 comp.jpg

    This coming week work will continue on the motors top end. Need to measure the cylinder volume from the top of the exhaust port, set the squish, measure the combustion chamber volume and adjust it. To do this I need to make a radius cutter.
     
  10. Scripto VU

    Scripto VU Dukes Speed and Custom

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    I think I will just read, re-read and process your build thread until I need a hair cut !
     
  11. Signal

    Signal XS650 Junkie Top Contributor

    Things have been very hectic here we are flat out trying to get this thing running so we can test it out at a meeting at the end of this month.
    We went racing last weekend and the XS went well and was still running at the end. of the last race. It was also good to get out on the track and have a bit of fun and catch up with our mates.


    Here is a brief update.

    I set the mandrel in the 4 jaw and recut the squish bands on the heads at 14 degrees. I did need to skim some metal off the face to get the squish right but after a lot of fiddling and measuring they are set. I went for 0.9mm.

    I had read that some of Yamaha’s spark plugs are not central to the dome. Partway through cutting the first one I stopped and rechecked the mandrel as I thought my setup was off. No it was the head, I didn’t think it would be that far off.

    Now the squish is right the compression ratio and squish band width needed to be set. Cylinders 1 & 4 will have CR of 7:1 and cylinders 2 & 3 will have CR of 6.8:1. If later the exhaust port is raised to 27mm the CR’s will be a bit lower. Gone for a squish band of 43% the bore area.


    Before I could do that I needed to measure cylinder and head volumes and work out what will give me the compression ratios wanted. I also had to make a radius cutter.

    This turned out to be a very time consuming job. I was also all at sea with the getting the correct or close enough radius for the radius cutter. Turns out when cutting partial hemispheres you need to find the chordal length.

    Adjusting the compression chamber volume was done by taking a tiny cut, then remounting the head, measuring, and then taking another cut until the desired volume is reached. Very time consuming but essential. It is all taking a long time as if you take too much its a case of hard luck start again.

    2019_1002RD7000046comp.jpg
    Its pretty crude but does the job.

    The seat unit has sanded up well and another seat has been made by our friend for his bike.
    Next to make the side wheel guard and grab handles.
    2019_1002RD7000038 comp.jpg

    The motor is starting to be assembled now the bottom end is together and in the frame.


    2019_1002RD7000039comp.jpg 2019_1002RD7000040comp.jpg
    There is still a mountain of work to do, but we will keep chipping away at it.
     
  12. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    Can't wait for this to come together for you! :heart:
     
    Jim and MaxPete like this.
  13. MaxPete

    MaxPete Life with Lucille...I suggest, she decides. Top Contributor XS650.com Supporter

  14. Jim

    Jim I have a plan. It's something to deviate from. Top Contributor XS650.com Supporter

    You just ABSOLUTELY GOTTA do a video of the first run. Please.... :D
     

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