Hi all, not used the Nevada for a while, but this year’s going to be different! (?)
Ever since I had the bike (only done 4500 miles) it’s suffered from poor (jerky, erratic) slow running, particularly when cold but even when hot it’s never felt right. Even at wider throttle openings it never feels happy. Always feels (and sounds) as if it’s being strangled, gasping for more fuel. Overly-lean mixture to pass emissions tests I guess, but it’s very annoying. I’m sure there’s a nice engine trying to get out but unable to do so.
I’ve tried a Finebau gadget, helped a bit but didn’t cure it, can’t reach the manufacturer now so can’t get any help there. Using super unleaded fuel but makes no difference.
I know this is (was?) a common problem with these bikes, has there been any progress in the last couple of years in finding a fix for it??
I think that the Nevada may be similar to an early model V7 like my Classic made in 2011.
If so I may be able to help.
Firstly check that your inlet and exhaust valve clearances are correct, generally 6 thou inlet and 8thou exhaust. This needs checking with the engine stone cold.
Make sure your spark plugs are set at 27 thou.
Do you have a laptop? If so download GuzziDiag (free) from Griso.org and buy the recommended connection lead from Lonetec. You will need a pair of vacuum gauges, even if you cannot get GuzziDiag.
Close both throttle by-pass screws, these are accessed from beneath the throttle bodies, the screw housings are cylindrical features cast in to the throttle bodies, about the size of a fat cigarette.
With the vacuum gauges connected, run the engine until reasonably warm, not red hot! Then with the throttle set at about 2-3000 rpm on the twist grip, balance the throttles using a screw on the left side of the engine beneath the left side throttle body. This screw adjusts the relative position of the right throttle body as against the left one. The vacuum gauges should be nice and even.
Let the revs drop back to idle and check the gauges again. Open the throttle by pass screws to achieve an idle revs of about 1150-1200 rpm while keeping the gauges balanced.
If you have GuzziDiag, now it the time to reset the TPS using Mark Bayley’s instructions that come with it.
It took longer to type than to do!
Many thanks for all that detailed info David, the Nevada engine is, so far as I know, very similar to early V7s. I’ll read, learn, inwardly digest and then have a go just as you describe. The laptop won’t be a problem, where would I obtain vacuum gauges to suit the Guzzi? Are they special or would any do the job?? Cheers, Peter
I use a differential pressure device using two ball bearings in a circular plastic tube that I bought off eBay years ago. Very easy and accurate but I cannot see them offered anymore.
Davida do very good vacuum gauges. I live in Hampshire North of Petersfield and you are welcome to visit once this coronavirus situation is over.
Thanks for the info, I’ll investigate further. As I live in Chester it’s a bit of a trek to Hampshire but many thanks for the offer. Strange times indeed!
I’ll have plenty of time for a few weeks to play with the bike so maybe I’ll get somewhere. Cheers, Peter
By the way: I had tried a Finebau Forge device but could not find the “Goldilocks” setting to get my bike to run properly. It seemed to be b@ggering up the ECU, they appeared to be fighting each other. In the end I took it off and started from scratch with live help over Facebook Messenger from Mark Bayley in Australia who is Beetle.
Yes I’ve not had much success with the Finebau device even though others seem to have. I think I’ll take it off and start from scratch.
I’ve resisted Facebook up to now, but there seems to be so much data/info/chat available on there now that I don’t think I can avoid it much longer. I’ve also found some useful info on www.guzziriders.org forum, so I should have plenty of stuff to go at during my enforced isolation…
Get your battery droop tested and some new plugs. My 07 Nevada suffered the same and improved dramatically with a fresh battery, fuel, plugs, a plus 200 mile day and then regular use. If you are going to lay it up for more than a week, brim the tank too. More than two weeks, take the earth strap off the battery too.
You can make a simple manometer using just petrol tube, a piece of wood and some coloured fluid (full instructions on guzziriders). I`ve used mine to successfully balance my RT1150 and to balance the carbs on my Monza.
In the days when I balanced the twin SU Carbs on my MGB, I used to use a length of plastic tubing to balance them.
With the engine running, put one end of the tube in your ear. Put the other end into the air intake of the 1st carb. You will hear the hiss of the air. Then put the other end into the 2nd intake. If the hiss in both intakes is the same, then the throttle bodies are balanced.
If the hiss is different, then they are unbalanced, and you have to adjust the throttle balance screws until you achieve a unity of sound.
I had a Gunson device, called a Carb-balancer I think. I seem to remember it had a conical plastic end and a simple flowmeter which you stuck in one carb intake, then the other. I used to prefer Triumphs to MG’s but seemed to work OK on twin Strombergs on the Vitesses.
Can anyone tell me the torque settings for the valve cover bolts? My so-called workshop manual doesn’t list them- in fact all the engine strip and rebuild info is missing, so I think I don’t really have a workshop manual although it’s genuine MG and describes itself as such…