V7 Classic Hot Pot

My 2009 V7 Classic runs with the offside pot hotter than the nearside: the exhaust header “blues” quicker and with much greater overall colour than the other one.

I’m running Iridium plugs; the bike starts perfectly, ticks over like a clock, has the power it should and is returning just over 60 mpg. One pot does “pop” on the overrun - I don’t know which one. Inlet and exhaust ring gaskets have been renewed.

Tappet clearances are spot on - the plugs are showing the same colour (if anything, a tad lean, but basically equal).

At the BMF Show last weekend, I saw another V7 with the right exhaust more blue than the left. Is this a normal trait of the V7 Classic?

I guess the throttle bodies could be “slightly out of sync”, but with my bike having a single lambda sensor, both injectors will be getting the same brew-mix.

What do other plastic-tank V7 Classic owners have?greybeard622013-05-20 20:47:24

Popping on overun is more often air getting into the zorst. one hotter then the other could be a tappet tight as well, these are the easiest to look for.

IF you have a rubber mount throttle body to inlet they can get loose or even a crack in them that also causes popping

I had this V7 phenomenon explained to me as differences between header chrome finish, quality control being less than in the medical appliance industry. Identical spark plug appearance after 6k miles supports the theory, and the pipes have evened out the blueing to roughly the same now.


May be less than helpful but…The Tonti framed bikes (which bear only limited technical resemblance to the V7) caused a lot of head scratching due to running hotter on the right than the left.You’ve covered the key aspects as noted in your OP.All the bestSteve

I thought the exhaust was stainless steel thoughout.I tried triple platinum plugs about 20 years ago on my lemon. Threw them away on the M6 and have been using standard ever since.On difficult to change Jappery they make sense but not on easy maintenance Guzzi’s.

I agree Ian I tried the Spitfire plugs, swapped them for standard then a couple of yrs ago got some Platinum plugs, they were on a “special” in Halfords, went back to standard. Guzzis well certainly the 2 valve per pot are low tech compared to the Jap and 4 Valve per pot engines.

On my 09 V7C it’s the left side that runs hot and has more bluing on the pipes. The right side runs a little rich, which probably prevents it from getting too hot.

Interesting - any idea why one should run hotter - both sides get the same, single lambda signal from the ECU? I can see the quality control issue (I expect left and right headers are produced separately, i.e. are not chromed as a pair), but I can find no obvious fault with ignition, plugs, tappet clearance, port gaskets, throttle bodies,injectors, sleeves. Sure enough, an air leak at one of the joints (silencers/balance pipe) can cause overrun ‘popping’ but blued headers is a temperature-based matter, before the exhaust system.

Apart from anything else, it’s a pain having to constantly remove the blueing.greybeard622013-05-24 20:22:49

To avoid putting the OP off.

I use iridium plugs for the outer and noticed a lot quicker starting from cold (twin spark big block engine). Maybe my imagination but have absolutely no problems with them and they should last a lot longer than the standard plugs and perform a lot better.

Platinum plugs are the standard fit to MODERN big block Guzzi’s by the factory! Things have moved on since 'back in the day!

NGK PMR8B laser platinum spark plug for inner plug application on late model dual plug head models. Original Guzzi code 05717030. Breva 1100, Griso 1100, California Vintage, Norge 1200, Sport 1200, Griso 1200 8V, Stelvio 1200, Breva 1200, 1200 Sport 8V, Bellagio 940.

I have stainless exhaust on the Bella but the quality of the stainless needs something to be desired requiring constant cleaning. Almost2013-05-24 06:47:46

On the difficult to change inner plug yes, not required on a low tech bike like Guzzi’s.My V11 ran on standard plugs fine and the engine is not that different.As for cleaning the bluing off, I wish I could see mine under the burned on oil residue.

The hard to get at inner plugs are fitted to all the CARC 2 valve engines.
Brian UK2013-05-24 09:44:04

Yes I know, I should have made it clearer.My view is that the expensive plugs are designed to make service intervals longer. This is not needed on single plug Guzzi’s as far as the plugs are concerned.I buy my plugs in 10’s, always carry a spare pair and the moment the bikes is difficult to start or runs badly I fit the spare pair.I could then probobly clean and regap the old plugs but for the cost it is not worth it.I have not owned a 2 plug engine yet so have no experience on them but my initial take would be to continue the same policy.

I have all the “SP” on twin-plugged BIG blocks ( I changed the twin-plugged Breva V1100 for a younger V7 Classic) - what I have is a V7 Classic,small block,with one hot and one cool pot. I have no spark plug problem (nor starting/tickover or dynamic power, issue), but a temperature imbalance between the pots which “blues” my offside exhaust and silencer.

Does anyone have any relevant suggestions how I might resolve this, or do I simply assume the RH system is more temperature sensitive than the LH?

Dunno about the small blox but the older bikes are timed up on the right then adjusted for left. best to ask a good dealer

On the new small blocks the ignition timing is done from the RPM sensor, I think, which is probably on the camshaft. As said, there is only one Oxygen sensor, so both injectors should squirt the same amount each time.One injector could be a little clogged up, making that side weaker. Try some injector cleaner in the tank, over a couple of tankfulls, it may just do the trick.The only other thing I can think of is to swap the injectors side for side, but that gets a bit involved. Do you have the workshop manual? It describes the revolution sensor in the electrical section P44.It also shows a picture of it in the engine from vehicle section, P77.
Brian UK2013-05-25 10:18:08

As Brian said, sending the injectors out for cleaning is a good idea. On my V7C a shop found them surprisingly clogged after only a few years. Use a “real” cleaning service, as opposed to a shop just pouring something into the fuel tank. I’m in the USA, and sent them to RC Engineering; http://www.rceng.com/Fuel-Injector-Cleaning-P43C0.aspxI hope there’s a similar service in the UK.Another idea is checking each side for a leak in the intake lines. A leak can make one side run lean and hot. To test: while the bike is idling, spray carb cleaner around the intake joints. It the idle changes, it indicates a leak in that area. If the idle goes up when spraying at the leak, it means that side is too lean (and might be hot).

sign2162013-05-25 15:30:37