Hey guys I have a couple questions about a bike I'm working on. Bike is a 14 streetglide special. He had a 120R put it in before he took delivery of the bike. Bike has around 15000 on it now. After doing about a 1000 mile round trip weekend he pulled into a town and engine started rattling. Bad enough he shut the engine down and called us for a trailer. We get the bike back to my place and it fires right up but there's a rattle coming from the front left of the engine/primary, then it just dies. My first thought is compensator. We put it on the lift and tear into the primary. There is a little wear on the ramps of the compensator otherwise it looks good (I've only seen one obviously bad one so not a lot to go off of). Will these springs wear out without much wear on the ramps? Is there any other known problem areas with these 120's? One more question. This also developed a base gasket leak in the last couple thousand miles. It started as a seep then changed to a full on leak. It's coming from the base of the rear cylinder right at the case seam. Any ideas what would cause this? Could the case have shifted causing this leak? We will most likely be tearing it down and doing a 124 but I want to make sure it doesn't leak when going back together. Sorry for the long post just wanna make sure all the information is here. Thanks for any help you guys can give me.

 

Why would a bike just die if the compensator was bad?

 

My deuce did close to the same thing (107) at idle it did a kick back type thing and killed it

 

Lifters are a known issue

 

Yeah I read somewhere they're only getting 10-12k out of them. We're planning to change them out when we bump it to 124. Hoping to figure the noise problem out so I know if we need to go into the bottom end or not before tear down. I'm a little nervous there as I've never went into the cases.

 

Could be a multitude of things, first off have someone bore scope the cylinders. May have a bad piston. Could be a lifter but likely wouldn't cause it to die. Could be a pulled stud or broken nut and you have a head gasket leak. Keep in mind noises travel. Never have been a fan of the 120 engines. Seen too many issues and too much hodge podge of parts assembled at the factory. These engines were first advertised as having SE camchest parts etc but the truth is you just never know what you will find from one to the next.
Edit: nothing to be nervous about going into the cases. very very simple and if you can do the top you can certainly do the bottom

 

Thanks good to know about the bottom end. I think I've done 5 top ends now. All fuel Moto 107's with the exception of a 103. Glad to know its not as much to worry about as I thought. We pulled the primary as I said and also drained the engine oil to see if there was excessive metal in there. Nothing to bad in either. My thoughts are to put in a new compensator (I have one on the shelf along with the Hayden tensioner that were intended for my deuce) and refill fluids and see what happens. If the noise is still there we'll diagnose further. Compression test, leak down etc. I ran a bore scope in through the plug holes and nothing seemed out of ordinary in there. Pistons and valves were visibly good.

 

Are you sure that the engine dying is the result of the noise?

Have you checked for a loose battery cable or made sure that you have the correct fuel pressure?

Treat each problem separately and you will spend less time fixing things that are not broken.

 

Yeah that makes sense. It all came at the same time so assumed it was all linked. You make a very good point though.
Now for an update. Got the primary back together last night and added fresh oil to the engine. Fired it up and it's all the same. We used a mechanics stethoscope and it looks like the noise is coming from the lifters. It looks like we'll be tearing it down and doing a 124 anyway so those will be replaced in the process. Now do you guys think there'd be any benefit in doing a compression test before tear down? We're planning on sending his jugs and heads to fuel Moto for the bore and head work. Should I be checking anything else for the reason behind the base gasket leak? I generally pull the studs out of the case and use red loctite and torque back to factory specs in case one has backed out. There's a ton of money dumped in this bike already I just wanna make sure it goes back together without a hitch. Thanks for the advice guys it's appreciated

 

I've had a lifter explode that took out the cams/cam plate and bent a push rod. Also had the rear base gasket start to leak, the 120R has an actual gasket. Replaced the gasket and haven't had an issue since.

I also went through three SE comps, the 120 eats the ramps up bad. Replaced with a baker and comp and haven't had an issue with the bike for about 8 months.