Boiling sound from the primary cover

07 XB 12. Just got back from a 1hr ride and around the primary cover it sounds like something is boiling. I did notice that the fan came on a couple of times while i was riding, witch it hasnt done before. Everything seems to be fine, clutch works fine, goes into gears fine, but just concerned about the boiling sound. THKS for youre input

might be time to change out the primary fluid; 1 quart fills it up just below the bottom of the clutch pack.

i think ive had the oil in my swing arm boiling a few times after an hours ride in 100+ degree heat

when it is hot,100+ degrees, my breather smokes like a chimney after a hours ride

As you are doing the fluids check the Air Vent coming up from the Transmission. Make sure there is no kinks or it is melted from the Heat or clogged. Amsoil 75/90 helps with the Heat issues due to no cooler is on the Transmissions of the V Twin Engines. The 2010 fan Program works well for that problem. It does run the fan a Lot but it's cheaper to replace a worn out fan than all the other problems Heat Issues will cause to an Engine, & Transmission. Sometimes also when some wash the bikes the Rubber Boot where the Clutch Cables adjuster is covered gets sloppy or burned over time a little water can get in there slip inside the cable housing and cause the same problem. If it's milky that can raise the Temperature also. MOST likely it's just heat issues and with Transmissions some clean Fluid helps every 2,500. miles. Also if you have fumes OR some smoking issues coming out of the Rocker Covers PCV valves area OR a Breather Re-route you might want to replace OR at least check the PCV valves & seals in the Top of the Rocker covers they can get clogged and they are known to melt a little causing a deformality in the pcv check assembly causing it to do exactly what you are describing. It won't hurt to check that so Keep it riding! *Jimi[cool]

i heard a similar sound from mine, decided it was actually fuel boiling in the lower end of the reservoir,i don't notice as much when there is plenty of gas in the tank,

i heard a similar sound from mine, decided it was actually fuel boiling in the lower end of the reservoir

Click to expand...

^That^ ....rest easy.

I think it would be pretty hard to boil the oil.... My vote goes for boiling fuel which is common on the XB series bikes.

RSS, heat barrier line inside & underside of frame, possibly ceramic coat headers, should help with heating fuel and keep your leg & seat cooler as well

Notro did your Fuel OR Cel light come on before the boiling noise started? I didn't think that anyone would run the Fuel that low due to the Cost of the Fuel parts. I've never run my bike that low on fuel before. It's possible that when that low it can make a boiling noise.I've seen Primary Vents boil and Fume due to Heat Issues Etc..Usually a repair was on the way from that. Low Fuel is Really bad for the fuel pump though. The fuel keeps the pump cool for longer life. Hope that is all that it was.*Jimi

from what i can remember i've had both boil at one point; i know when it was 100+ degrees my breather would end up smokin like a hibachi grill most all the time

seems like my swingarm as gotten hot a few, and def my gas tank on occasion. if ur trans hose gets pinched, the fluid finds its way up the clutch cable and u end up with less than a quart in ur primary, which ends up hotter on long rides

i heard a similar sound from mine, decided it was actually fuel boiling in the lower end of the reservoir

Click to expand...

yep same here

^^ +1. They really don't like sitting in traffic at stop lights when it's warm out. Orlando was brutal on mine this summer.

So it finally occured again after a short ride home from work. I started to take the primary inspection plate off, then had a light bulb go off. I took my keys out and popped the gas lid off and it gurgled and stopped. Anyone know if the gas cap has a vent or is it somewhere else. Thanks again for all your helpful insight and knowlege.

The Gas tank has a vent line that runs down and normally ends behind the LH heel gaurd plate. You can hear it REAL good if you listen there. It's all normal. Also Old or Bad gas can reach it's boiling point faster if that's whats happening here.

The Venting can cause the problem was hoping it would be a cheaper fix than the Fuel cel vent. The part number is #P0115.02A8B should come with the O'ring too! I've only changed a couple of those make sure the hose is clear first all the way to the rear of the frame left side like Stevenc150 is saying, it's easy to replace the part.Just up by the right front area of frame with the Air Box removed. Be easy on the screws holding it in. Should this be the problem. Make sure the part number hasn't been superceeded to another. H/D likes to do that a lot.*Jimi

Your stator could fry your oil, if it starts to go out. If your primary oil smells nasty, stator is burning your oil.