TOPIC:

Since I replaced the header pipes on my A5, which involved taking the rad off, I fancy the bike is running hotter than before and the fan comes on more. I have taken the rad cap off when she's cold and it seems full to the brim and the header tank is full.

Any ideas?

Thanx

If you're using after-market pipes (the original's are double walled & more insulated), it's common for the coolant to become heated by the pipes next to them. Common/best solution for that is usually just insulating the bottom rad hose. There's a multitude of insulating solutions out there for you to try. If you get a roll of it it's great stuff to put under the tank as well.

Also, if you've got any water mixed in there, try some water wetter. Upgraded fan blades like muzzi ones and a ZN fan switch are great upgrades for the KZ bikes as well.

I have been running a DG for 25+ years and have not seen any noticeable increase in coolant temp. while on the highway or in slow in-town traffic; as opposed to the stock exhaust. The lack of air flow while at several lights has always brought the temp. up quickly but again, I don't recall the stock (double layer)pipes giving any significant advantage. I did however install a manual fan-switch soon after getting the 1300 due to the quick rise in temp. (stock exhaust) when air flow was minimal. The advantage of manually turning the fan on when anticipating slow traffic is of great benefit. At highway speed my temp. gauge rides on the lower-line of the scale. I completely agree with insulating the lower hose. I recently submitted such a recommendation. To reiterate: Two wraps of heavier (6oz.) fiberglass cloth with two wraps ofAluminum self-adhesive HVAC duct tape. ( NOT the plastic/cloth-type "Duck-tape"). The fiber-glass wrap is the insulation while the aluminum cover-tape reflects the heat. I'm using the stock fan, run about a 50/50 coolant mix, original thermostat and (fan) temp.-sensor. If I was faced with an unacceptable high operating temp. range I'd perhaps start by checking to see where on my temp. gauge the fan was cutting in. This might suggest the fan temp-sensor switch may not be activating the fan soon enough to catch the rising temperatures. If I felt the fan was being turned on soon enough then I would likely remove the thermostat and test it to ensure it is opening at the correct temp. and opening fully. Hope this points you in a logical direction with a successful out-come.

Good suggestion from Scotch. I Don't have any experience with the after-market exhaust yet but mentioned the pipes since it had been talked about on the prior site/faq.

I also run the DG system and have never experienced any over heating, perhaps because I moved two of the coils from above the engine to facilitate air flow. I did use the "water wetter" stuff with my 50/50 mix of coolant and water.

Bill

I'm glad the "coil" location was mentioned. I did the GM conversion many years ago which placed the coil-block in the tool-tray. This does potentially open up the air flow over the top of the engine but this would be difficult to quantify. One could also rationalize that the DG (type) header would also cool down quicker due to the reduced mass of metal (single layer vs. double layer (stock pipes). Header-wrap would certainly contain/control the exterior heat transfer but from the numerous articles I've read, wrapping headers is the quickest way to destroy them due to the extreme internal temps. which (para-phrasing) "vaporizes the metal from the inside-out". In just discussing this concern with my local auto-parts guy he confirmed that some header manufacturers will not warranty headers that have been wrapped. So keep it simple: check the coolant mix ratio, check the thermostat for correct full-opening temp., ensure the fan temp. sensor is activating early enough to be of benefit, the fan is free-spinning and not partially seized and confirm the rad. is clean for max. flow.