the only thing you need to do is open up the valve lash. pull off the head and twist a valve with your fingers while turning it over. youll find that the intake valve doesnt close until its about 3/4" from tdc. thats no good for power obviously. shave the back of the valve stems a bit till you get some more compression out of it. like 3/4" from the bottom of the stroke is more better so you still have some overlap. itll wake it right up
Motorized bicycle build
- Thread starter ValleyCenter ACE
- Start date
- Tags bicycle board track racer build harley motorized
yup just dont overdo it. TRK usto do the same thing. he and I are the only ones I know of that do it like that without a feeler gauge. the only down sides are the rope gets harder to pull with all the compression but on 3hp engines its not as bad as the 5hp ones especially on the older ones with a small recoil. And you get a little more tickity tick noise from the lifters but its not bad. They seem to start better too.
Well I got that silly little intake valve in the block and I rotated the crank and the intake valve closes right as the piston begins the compression stroke. So the intake valve is only open during the intake stroke! Sooo would making the intake valve close sooner increase the performance on this engine?? Meaning that the valve would close before the intake stroke was finished, meaning (from what I know about engines) that the engine would be getting a smaller amount of the air fuel mixture. Please I need a little help! I would love to learn more about this!!
This engine is also a newer Briggs and Stratton it has the plastic cam shaft, I haven't seen if it has the thinner piston rings though.
This engine is also a newer Briggs and Stratton it has the plastic cam shaft, I haven't seen if it has the thinner piston rings though.
ok I wish you would have said its a newer one before. Im pretty sure they have a different design for a compression release. like a centrifical lobe on the cam that releases once it gets started so it can then make full compression. in that case I dont know what to do. probrobly not much you can do with that. still I would think youd be getting some release on the compression stroke when just turning it over. unless its on the exhaust side. did you check that? you dont need to pull the springs off to check. they will still spin fine when in place
Yeah I've torn the engine down all except take out the piston! It's a Lawn mower engine That's supposed to be vertical. I've done the necessary modifications to make it sit horizontal, I have done a lot of research and it will work just fine. I didn't say this before because I don't want an argument about how it won't work, Because it will ,but if anyone has any pointers to help me out I will appreciate it. So there's probably nothing I can do to adjust the valve lash. It's already sent up pretty nicely!
And the cam is just a simple plastic cam shaft nothing fancy. It also had an electric starter soo.. I don't know if that changes anything. When I get a chance I'll take a look at some other similar engines I have and see if they are the same way!
And the cam is just a simple plastic cam shaft nothing fancy. It also had an electric starter soo.. I don't know if that changes anything. When I get a chance I'll take a look at some other similar engines I have and see if they are the same way!
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intresting. yeah i figured something was up iv never seen a horizontal shaft engine with a plastic cam. How does it run without the added weight from the blade? I know some run crappy like that and some are fine. If things seem good with the valve lash youll have to make youre mods elsewhere. maybe a thin head gasket, clean up the ports and the flow in the cylender.
So I haven't given up on this build I just have been going to school and I have had no time to work on my bike.
I believe a few changes are going to have to be made to my design and what not.
First having bicycle pedals seems like it's going to be impossible because one of the sprockets is going to have to stick out very far from the frame.
I'm probably going to just restart from scratch...the frame the whole thing needs to be reworked and trying to fix the existing frame is going to be harder then starting from square one. No big deal. Let see if I can actually do this instead of talking about it.
I believe a few changes are going to have to be made to my design and what not.
First having bicycle pedals seems like it's going to be impossible because one of the sprockets is going to have to stick out very far from the frame.
I'm probably going to just restart from scratch...the frame the whole thing needs to be reworked and trying to fix the existing frame is going to be harder then starting from square one. No big deal. Let see if I can actually do this instead of talking about it.
Its too late now but your gonna lose power potential from the intake valve closing at the end of the intake stroke. As jeep2003 stated you do want the piston to begin popping up in the compression stroke before closure. The velocity of intake charge will push air in for a time after the pistonbegins moving up. Factory spec does go overboard and you should get a little power but you coulda made more.
Due to some resentment... Not that I don't like you guys,... Hahahahah!! ... But I will post once I finish the motor and have it running then you will see what I'm talking about. And in the mean time maybe a quick google search would reveal that there is a lot of information about how to run a horizontal engine in a vertical position....... So In the mean time I'll repost in like 15 years at the pace I'm going!
And just to stir the wasps nest the frame will be brazed together.... yeah the frame will be brazed together ... ooooohhhhhhhh nnnnnnooooo not a brazed frame....... HAh! So If you want to say " If it an't tig'ed... mig'ed.... or Stick'ed ?!!... or them wired feed'ed then it in't ..?.. Crap" Then don't comment! Sorry I would hate to get in a argument about it! Cheeers! Working On it now Guys!
And just to stir the wasps nest the frame will be brazed together.... yeah the frame will be brazed together ... ooooohhhhhhhh nnnnnnooooo not a brazed frame....... HAh! So If you want to say " If it an't tig'ed... mig'ed.... or Stick'ed ?!!... or them wired feed'ed then it in't ..?.. Crap" Then don't comment! Sorry I would hate to get in a argument about it! Cheeers! Working On it now Guys!