08 150RB hard to crank etc
  • Hytwr1
    Posts: 3
    Joined: Tue Sep 07, 2021 6:50 pm

    08 150RB hard to crank etc

    by Hytwr1 » Fri Sep 10, 2021 8:17 pm

    Hi all,

    So my daughter bought a '08 150RB that the seller could not start upon pickup. Her boyfriend was able to kick the heck out of it and get it to start so she bought it. So she bought this thing a month ago and has not been able to ride it since as she cannot get it to kick over. She had another one previously that she said kicked easy. She said a 300lb farmer she has been working with can start this one no problem, but she only weighs 105! :)

    Anyway, she brought it to Dad, the race car hotrod guy for work and I am being baptized as a motorcycle mechanic. Been searching the web for ideas and help and settled on this group. So I hope you can help me.

    She said when they try to start the bike they have to pump forever, it floods and if lucky can get it to fire up.

    She brought it to me with an allballs carb kit and that's where I started. Went through the carb that had a clogged pilot jet (replaced the 38 with a 42), goop in the hot start and generally looked like it has been sitting in the rain for a while or got water in it. I Installed the rest of parts in the carb kit and found said kit missing the mixture screw oring washer setup. Rounded up those, put it back together pumped the daylights out of it and only got a slight backfire pop. Spark is there with new plug and we have plenty of gas. I even tried starting fluid. So, now I am thinking valve train issue of some sort making it so hard to kickover.

    I checked valves and got the following readings. LH EXH .008 (.2032mm) INT .006 RH EXH .010 INT .004 (.1016mm). Current shims are LH EXH 2.18 RH EX 2.14 Both LH & RH Intake shimmed at 1.95.

    Being more familiar with old school v-8's than small engines how critical is that valve clearance on these? If my calculations are correct I need a 2.12 shim on the left exhaust and 1.90 shim on the RH intake to bring things to spec. Bought a hotcams shim kit I think has what I need. Anyway, before I go hunting shims I thought I would ask the experts here for some assistance.

    Oh, before I forget, when I wen to pull the cam I found the compression release stuck. Ho does one set that?

    I have service manuals ordered, but a lot times I have found those who do the work know ways to make thing work no in the books.

    Anyway, thanks in advance for the help and I look forward to your assistance.

    Bill

    Edited after I realized my calculations were wrong due tp forgetting to convert inches to mm.
  • User avatar
    JimDirt
    Posts: 4406
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 08 150RB hard to crank etc

    by JimDirt » Sun Sep 12, 2021 6:33 pm

    Welcome to the site !! \:D/

    As far as the valves , they are a bit off , my concern is the 0.004 intake , any tighter and it means the valves are closing and it will be more difficult to start , till it wont .... if you can get the Intake to both be 0.006 or 0.005 that should be a benefit to starting , but not sure it will cure the issue it will just assure that the valves are not causing it to not start , the Decompressor is another concern , it sounds like it is either not working , or the pin is broke , or something within the decompressor is not right , that is what is causing it to need a 300 lbs. guy to kick it ..so you need to look into what is not functioning with that system .....

    Have you verified it is getting a blue spark , and a snappy spark ?? , nothing yellow or weak looking ... this could indicate stator or coil issues , even a ECU/CDI .... You also mentioned it looked like it was left out in the rain .... is it possible that water got into some of the connections and they are corroded ??? ... unplug every connector on the bike and look at them and make sure there is no corrosion , that will kill any voltage , cause massive resistance , and make starting a issue ....

    Have you tried push starting the bike ... like get it going good and put it in 2nd gear , and see if it starts , if it does and runs fine , then I would look at valves as the cause (the tight intake you mentioned) they should be plus or minus 0.001 in. from the spec .

    The valve specs should be:

    IN: .006+- in (.16 +- .03 mm)

    EX: .010 +- .001 in (.26 +- .03 mm)

    A note on the shims , I believe the smallest shim will be a 1.25 , you can't go any less than that , as that is the final adjustment before valves need replacing , if you cant get to 0.006 with one of those , you need a valve job , they will be closed up which would cause it not to start and eventually a broken valve once the face wears thru (sucking a valve)

    Also while you are looking at everything , you need to verify the timing is correct ... 3 spots , 1) cam , there will be a triangle on the tower , left side front and a slash marks on the cam sprocket , the slash marks need to be level (like this - - ) the lobes on the cam need to be facing the rear of the engine around 2 0 clock looking from the left/ignition side, the small round plug in ignition cover , should have a slash mark and a notch .... the clutch cover will have a large round plug , it will have a triangle and a dot , they need to be lined up ... ALL 3 of those need to be aligned to know your timing is on ..
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho
  • Hytwr1
    Posts: 3
    Joined: Tue Sep 07, 2021 6:50 pm

    Re: 08 150RB hard to crank etc

    by Hytwr1 » Sun Sep 12, 2021 7:05 pm

    Jim ,

    Thanks for follow up.

    Yep verified spark and all that good stuff.

    As I started to take it apart to shim the valves I found the hard crank problem. The decompressor was stuck. Pic attached. As soon as I loosened the bolt just a smidge it snapped into position. So one problem down.

    Went in this morning and put a 1.90 shim on the intake that was close to no go and popped a 2.25 on the exhaust that was a little off. Checked everything and they are now spot on. Put it all back together and It fired right up for me.

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  • User avatar
    JimDirt
    Posts: 4406
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 08 150RB hard to crank etc

    by JimDirt » Sun Sep 12, 2021 8:32 pm

    Glad to hear you got it sorted out ... Yea the Decompressor is critical in making it easy to start .... I would however use some Blue Loctite , and put it on that screw so it does not back out , you do not want that screw falling into the flywheel area , it will create loads of turmoil , when you get your manual torque it to what it "should" be at and also use the Blue Loctite
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho
  • Hytwr1
    Posts: 3
    Joined: Tue Sep 07, 2021 6:50 pm

    Re: 08 150RB hard to crank etc

    by Hytwr1 » Mon Sep 13, 2021 5:49 am

    Glad to hear you got it sorted out ... Yea the Decompressor is critical in making it easy to start .... I would however use some Blue Loctite , and put it on that screw so it does not back out , you do not want that screw falling into the flywheel area , it will create loads of turmoil , when you get your manual torque it to what it "should" be at and also use the Blue Loctite
    Thanks for the help.
  • User avatar
    JimDirt
    Posts: 4406
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 08 150RB hard to crank etc

    by JimDirt » Mon Sep 13, 2021 11:36 am

    No problem .. ;)
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho

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