Bike won't start after cam and air cleaner change

[mmachine]

I take the vent plug out on almost every Big Dog with a higher-flowing air cleaner and exhaust. It's just helps the float bowl maintain it's level. IF you have spark AND fuel, you may want to make sure the little vacuum cap on top of the intake isn't dry-rotted (I see that all the time) and leaking. Though that shouldn't prevent it from starting, It will make it run rough and hard to start. There's also a white plastic insert in some Big Dog gas caps. I've seen these stop working and prevent the tank from venting so fuel won't flow. We used to take these out on brand new bikes at the dealership - caused all kinds of problems. Like everyone else, I would make sure you have fuel and spark first.

 

[BadBrad]

If it ran fine before, there's no reason why it would lose compression just from changing the cam, as long as it was installed properly. I think I would go back and remove the pushrod covers, pull the plugs, put the bike in 6th gear and rotate the wheel. When the front intake pushrod is in the up position, make sure the rear intake doesn't have any slack and repeat this for all 4 pushrods. You should be able to twist the pushrod with your fingers, but there shouldn't be any movement vertically. If you didn't adjust the pushrods properly, they may not be opening the valve to allow fuel inside the cylinder.

 

[MARV]

If it ran fine before, there's no reason why it would lose compression just from changing the cam, as long as it was installed properly.

if the rods are adjusted too long the valve wont fully seat = no compression

I've got spark and I've got fuel(Harry the petcock was turned on). I did have fuel coming out of the air cleaner though.

he has fuel, he has spark, he says the cam is installed right, cant adjust timing with the stock ignition, id think itd be time to head to auto store for a $25 comp tester to rule that out.

just not sure who "Harry" is though

 

[HMAN]

just not sure who "Harry" is though

Uh.....that would be me.:lol:

 

[BFB]

like it was said earlier,check you don,t have the plug wires switched. Did that once and it will not start.

 

[BadBrad]

Sul has a point there. If pushrods are adjusted too long, the valve won't close. May be best to just start over with re-adjusting all 4 pushrods. I think the manual says 4 full turns (24 flats) from zero lash. Be sure to allow 15 minutes between each rod to allow the lifters to adjust. You should be able to twist the rod with your fingers before moving on to the next.

 

[slam]

I talked to a friend who had the idea that the timing may be out 360. Since I had spark and fuel, I figured I'd try it. I pulled the cam, turned the crank 360 and reinstalled cam. I guess my temper got the best of me because some how, I adjusted the pushrods wrong and bent 3 of them(I spun the rear wheel. Good thing I didn't try starting it). I got the new rods in yesterday(quickies). Installed yesterday and adjusting rods today. I'll let yall know how it goes. I also need to post some pics of new paint and mods.

 

[pknowles]

don't mean to be slamming you Slam, but ain't 360 degrees right back where you started?

 

[DRBarnhart]

don't mean to be slamming you Slam, but ain't 360 degrees right back where you started?

360 on the crank will get you 180 on the cam so the crank is back where it started but the cam isn't.

Were the timing marks lined up before the old cam was removed?

And not to be the potential bearer of bad news here but I'd be concerned about the valves and pistons if I had bent pushrods...

Dennis

 

[pknowles]

Thanks for straightening me out Dennis.

 

[Th3InfamousI]

360 on the crank will get you 180 on the cam so the crank is back where it started but the cam isn't.

Were the timing marks lined up before the old cam was removed?

And not to be the potential bearer of bad news here but I'd be concerned about the valves and pistons if I had bent pushrods...

Dennis

I agree Dennis! I'm concerned about the valves as well.

I thought you said you DID try starting it? Since that's the whole point of this thread. Subject: Bike won't start after cam and air cleaner change

 

[MARV]

As long as the timing marks on the cam, pinion and breather align then he was good. Sounds like his rod adjustment was wrong.

Question is... Were the timing marks aligned after install?

 

[DRBarnhart]

As long as the timing marks on the cam, pinion and breather align then he was good. Sounds like his rod adjustment was wrong.

Question is... Were the timing marks aligned after install?

:iagree:

Kind of sounds like the rods were adjusted too long the first time then WAY too long the second time...

Dennis

 

[Five Five]

Hey Slam ... well it looks like your getting there....you may have bent a few push rods, but hell thats how you learn... i have to give you a little respect because at least your trying

 

[05 old dog]

so how do you check to see if crank and cam are where they are suppose to be and not 180* off...ive got my cylinders off and installed a new cam...moved the back wheel alot trying to get pistons up and off to clean things up...i aligned all marks but did not know about the 2-1 on crank and cam...

 

[MARV]

Doesn't matter. As long as the cam and pinion gear are aligned your good.

 

[05 old dog]

whew...ok i should be good...thanks SUL...

 

[slam]

Thanks Five Five. I was determined to do this myself but I finally had to tap out. I'm sure I messed up a valve. I brought the dog to a shop to get fixed. I should hear something tomorrow to see what I secured up. I guess I got a little over my head on this one, but sometimes, that the only way to learn. Hopefully I'll be up and running soon. I'll post some pics then.

 

[Th3InfamousI]

Thanks Five Five. I was determined to do this myself but I finally had to tap out. I'm sure I messed up a valve. I brought the dog to a shop to get fixed. I should hear something tomorrow to see what I secured up. I guess I got a little over my head on this one, but sometimes, that the only way to learn. Hopefully I'll be up and running soon. I'll post some pics then.

Keep us updated man! Be good to hear where you went wrong, I hope no damage!

I was pulling for ya!

Nothing wrong with trying to do it yourself! Personally I would rather spend more money and learn a few things along the way, knowledge is power. Either way, I am rookie wrench myself and was terrified of the cam change because of the pushrod adjustments (Still Confused about em) I commend your determination. You tapping out discourages me from trying myself. I got the WirePlus mod which I'm going to hopefully do this weekend, scared about that too. :down:

 

[Bowhunter]

Th3InfamousI, you can do the Wire Plus if you just take your time and be very careful of clipping the correct wire, just take it one wire at a time and you can do it. The cam swap is actually considerably less time consuming than the Wire Plus. I took a pic of the connectors with my digital camera and blew it up on my computer to a full page size so that I could count the pin locations to get to the correct pin. Much easier than trying to see those little numbers with my 56 year old eyes. Good Luck!