TDM850 - TDM900 : common issues


These problems are mostly specific to TDM family (including XTZ & TRX), but some may also appear on other Yamaha models. Check carefully these problems when purchasing a used machine, along with the usual checkings.

Note : "common issues" does not mean that they appear consistently on all machines, but simply that these are issues that occur sometimes during the life of the machine, with a frequency that varies depending on year of built, climate, usage... It is obvious that the corrosion problems occur depending on the climate, the use of salt on the roads, the frequency of cleaning and lubrication operations, etc.
It is also obvious that little or no maintenance at all will lead to reliability problems such as those described here, but also many other problems.

Don't forget that maintenance & prevention are the best way to avoid issues.

TDM900

Engine / Low revs jerkiness

This is often a very subjective issue - I've personally not experienced it, or maybe just a little at the begining - and there are a multitude of causes :

Objective causes
• The airbox flap : one of the main cause of the problem, resolution is easy - have a look at this page. The flap prevents the engine from breathing air properly at low revs.
• Other main cause of engine jerkiness : adaptable exhausts mufflers.
The OEM mufflers offer some resistance to the passage of gas. Fuel mixture is determined according to this parameter, among other parameters. When different mufflers are fitted, it is likely that the reason is to get more power from the engine : they offers less resistance to gas flow (this is also due to the absence of catalytic converter). Unlike the air intake side of the engine, there is no pressure sensor for the exhaust gasses to allow the ECU to recalculate the fuel mixture when changing the exhaust system. This therefore leads to a fuel mixture too lean and also to some problems like engine jerkiness, blue exhaust pipes, and sometimes exhaust valves failures. To address the issue, it is necessary to enrich the fuel mixture (see the Mode CO page) or to put a magic electronic box (ie PowerCommander) which does almost the same job. An additional box in most cases will only put thing as they where before the new exhausts where fitted, with the side effect to cost a lot and also gain at most a lonely horse power !
• Adjusting the fuel mixture : it is factory set too lean - the EURO reg requires this - it should be a little richer to allow a more pleasant usage. Have a look at this page.
• Not enough free play in the throttle cable : when set too thight it causes difficulties to properly control the engine and can make the bike impossible to ride.
• Not enough slack on the drive chain makes the machine jerky at low revs. As a bonus it causes abnormal stress to the gearbox shaft bearing. The normal slack should be 50 to 60mm (or 10mm between the top of the chain and the bottom of the swingarm).

Subjective causes
• Proper usage of the engine is more important with a twin : avoid too low revs, inadequate gearbox selection, etc. You may experience such problems if you're more used to ride four cylinders bikes. A twin has more torque at low revs, town usage requires frequent use of the clutch. Avoid low revs (below 3000rpm).
• Frequent town usage : the torque curve of the engine makes town rides not very enjoyable, unless you make a frequent clutch usage and adapt the gearbox ratio - it therefore requires some experience !
Remember that the TDM900 was designed primarily for roads with curves...

Problem solving, see above and also :
• Work on admission: inactivating the airbox flap helps a lot. You may also adapt another air filter (K?&N or other brand) and / or add openings to the airbox.
• Adapt your riding style to the specific nature of a twin engine.

Engine / defective ECU

Defective ECU were fitted on the early TDM900 shipped before june 2002.
Theoricaly all these models were modified by the resellers, a new version ECU was fitted in place of the defective one under warranty.
• Years : before june 2002.
• Check : Defective ECU.
• Expenses : free of charge (part & labour).

Engine / Throttle position sensor (TPS)

Years 2002 to 2005 TDM900 where fitted with a sometime defective throttle position sensor.
These defective sensors present the following symptoms :
• irregular engine rpm at idle, sometimes the engine stalls with no reason.
• dash self-resets.
• irregular variations of the sensor output voltage (non-linearity).
All TDM900 with faulty TPS were being recalled by late 2006 by the importer for exchange of the TPS as a safety recall (no warranty delay concern). Each modified machine is listed by the importer, ask the dealer with the serial number to check if the exchange was made.
• Years : 2002 to 2005.
• Check : Checking the TPS.
• Difficulty : easy.
• Expenses : free of charge (part & labour).

Engine / Cam chain tensioner

Some machines from 2002 to 2004, no matter the mileage, are subject to this issue : the distribution becomes noisy, first from time to time, then more frequently. The tensioner needs to be replaced with a new modified one - unfortunately off-warranty !
• Years : 2002 to 2004.
• Check / Repair : Cam chain tensioner.
• Difficulty : fast & easy.
• Expenses : tensioner + gasket - approx. 115-120¤.

Engine / Cold start mechanism

The cold start fast idle (hot wax mechanism) may have the sliding piston seized up by corrosion, dirt, etc. When it happens, the idle speed is too low when the engine is cold, or too high when the engine is warm. It is then necessary to clean / lubricate the piston. This problem seems to occurs more frequently on machines subject to a cols & humid weather, as found on some islands north of the Channel.
• Years: all.
• Workaround : Cold start issue - quick repair and also Cold Start issue - complete workaround.
• Difficulty: fast & easy (first option), long and painful (second solution).
• Expenses: none : lubricate.

Engine / Overheating

During urban riding, the temperature indicator goes up and the fan quickly quicks in. Many users worry about that because the temperature needle often flirts with the red zone. There is actually no reason to fear a fatal overheating which could damage the engine head gasket. The radiator looks rather small although it is big enough for the normal usage of the machine : riding above 40°C with the engine not overheating is no science-fiction - I mean in case you live in a country with such temperature... The radiator fan correctly fulfills its duty to lower the coolant temperature back to the correct level.

However some points are to be checked :
• correct coolant level, no leaks in circuit - the filler cap is located at the highest point of the circuit (machine on the sidestand) there is no need to fear an air bubble in the system.
• check the expansion tank.
• the radiator is ok.
• the thermostatic valve is ok.
• check hoses - unobstructed.
• radiator fan works ok - use the DIAG mode #51 to check.

The radiator must be checked so that no dust nor insect (or mixture of both) block the air flow through it. Radiator fins must be straight. No "decorative" protection grid should be used as is usually restricts the air flow. Let me remind here that it is totally useless to obstruct the radiator during winter in order to warm the engine more quickly : the thermostatic valve is designed to do that job !

The TDM900 was designed for curvy roads rather than streets. It is therefore advised in the latter case to avoid anything that might cause engine overheating : speeding, excessive acceleration, high-revs. In two words : ride cool !

Chassis / Front brake calipers

The front brake calipers/pistons have tight machining tolerances, consequently the pistons may seize in the calipers due to dirt that settles quickly on it. Only two, or even one piston remain operational, which creates a loss of braking efficiency and asymmetric wear pads. The solution is remove the calipers, bring out (but not fully) each piston one by one to perform cleaning. There are commercial products for cleaning brakes, but I prefer simply using brake fluid, which is not only very effective, but also perfectly compatible with the brake seals.
• Years : all.
• Workaround : break system maintenance.
• Difficulty : include as part of the annual maintenance service.
• Expenses : none / some brake cleaning fluid.

Chassis / Rear suspension linkage

The rear suspension linkage is a device made with a rocker and arms around the swing arm & the shock absorber.
All joints are equipped with needle bearings that require annual maintenance and lubrication. This also applies to all ball bearings of the chassis.
The risks for non lubrication are corrosion & premature bearing wear - even more during winter with salt on the roads. The worst problem is with the rocker which may seize on the support frame, with a likely failure.
If this happens, the repair becomes problematic because the chassis needs to be welded !
• Years : all.
• Workaround : Remove & service the swingarm.
• Difficulty : include as part of the annual maintenance service.
• Expenses : some lithium grease & MoSo2 grease.

Chassis / Rhs drive chain tensioner

The right-hand side tensioner is not lubricated by the proximity of the chain and can suffer from simple corrosion to electrolytic corrosion (steel against aluminum) mainly in saline environment (seaside and winter).
Seizure of the screw may happen, or worse : it breaks !
The best solution is prevention : protect the screw with grease (ie each time you lubricate the chain).
In case the screw is already seized : use WD40, wait and hope.
In case the screw breaks apart : use a tap to install new threads and put an helicoil.

Electrical / HT coils output

HT-leads / coil output may sometime present an annoying short-circuit problems, with all HT current going to the chassis instead of the spark plug, leading to a non-working corresponding cylinder. This issue occurs mainly in cold & wet weather, after heavy showers or high-pressure cleaning, on misty mornings after spending the night outside, etc. A dirty HT lead / coil output may also facilitate the problem as dirt makes a good nest for moisture. The issue is easy to prevent or overcome : use heat-shrink tubing (with thermoplastic adhesive on the inside), or some self-amalgamating tape. Carefully clean / dry the HT-lead and the coil housing beforehand (do not use WD40).
• Years : all.
• Difficulty : easy.
• Expenses : cheap, get some heat-shrink tubing or self-amalgamating tape.

Electrical / Main switch

False contacts occur sometimes with the main switch, this is due to its relative sensitivity to overloaded key-rings (common issue with all Yamaha). An Error #19 may appears on the dash, with no engine firing.
The best workaround is prevention : use only the ignition key and keep the other keys in your pocket. This is also a very good method to prevent keys loss. Never clean the main switch with WD40, use real contact-cleaner instead.
• Years : all.
• Difficulty : easy to prevent.
• Expenses : change the main switch in the worst case.

Electrical / Alternator

Apparently this issue is caused by overheating and appears mainly under hot climates with machines having more than 100,000 km : coils overheat and melt the enamel insulation of the coils winding, which then cause a premature death of the coils. The engine will run as long as the battery can feed the ECU, injectors & the ignition coils. As the Reg/Rec of the 9er is rarely to blame, a complete check of the alternator is required.
• Years : all.
• Check : how to check the stator resistance with an ohmmeter.
• Replace : everything you need to know about replacing the alternator stator.
• Difficulty : easy to check (ohmmeter), changing the alternator is not so hard to do.
• Expenses : change or repair (coils rewind by a specialist) the alternator.

Misc / Fitting the air filter box

Not really a problem, but it should be noted that fitting the air filter box on the injector throttle bodies is particularly tedious (to be polite).
There is a very simple solution :
• Open the air filter box and remove the air filter element.
• Place the lower part first : much easier!
• Tighten the hose clamps on the throttle bodies.
• Tighten the front box screw.
• Place the air filter element and the upper part.

TDM850

Gearbox

A common issue with the TDM850 until 1998. The gearbox is imprecise, noisy, temperamental, etc. This is probably due to a mechanical design problem, but break-in seems to be also a cause. Not much to do except avoid using the gearbox roughly. Frequently the transmission chain is in cause as the gearbox is very sensitive to the chain slack being too tight. Chain slack must be 40 to 50mm, machine upright and unloaded.
• Years : 1991-1998.
• Difficulty : easy.
• Expenses : none, check the chain slack is ok.

Oil consumption

A very common issue on TDM850s until 1998, multiple causes. Oil consumption may reach 1L/1.000km.
• Years : 1991-1998.
• Check / Repair : Oil consumption.
• Difficulty : varies.
• Expenses : varies.

Frame crack

The 3VD chassis has sometimes the tendency to crack on the inside, near the gearbox sprocket location. The main cause seems to be a too high mechanical constraints due to excessive use of the machine.
• Years : 1991-1995.
• Check / Repair : check the inside of the frame, left hand side, near the axis of the swing-arm. In case a crack appears you need to fix with no delay.
• Difficulty : rather difficult, the engine must be removed.
• Expenses : none in case you do all the repair (welding station required), otherwise...

Gearbox sprocket

The nut on the gearbox output shaft sprocket is not well secured. It may come loose on the shaft, destroying the thread.
• Years : 1991-1995.
• Check : remove the sprocket cover. The lock washer must be properly bent and shaft thread intact. Also check the nut is properly mounted (flat side on the outside).
• Difficulty : easy to control, repair problematic if the thread is dead.
• Expenses : expensive in worst case.

Carburetor emulsion tubes / needles

The carburetor emulsion tubes/needles is a well-known issue on 3VD (MkI) TDMs. Emulsion tubes wear quickly and fuel mixture is not correct, with all the usual consequences : higher fuel consumption, lower engine power, explosions in the exhaust, etc.
• Years : 1991-1995.
• Check : check mixture.
• Difficulty : medium, removal of carburetors needed.
• Expenses : new parts as a minimum.

Valve seals

They wear quickly, especially when using a different exhaust muffler : this often causes a rise in the exhaust gas temperature. The exhaust valves may also be destroyed for the same reason.
• Years : 1991-1995.
• Check / Repair : check compression and oil contamination by exhaust gases. The repair requires the removal of the cylinder head.
• Difficulty : difficult.
• Expenses : mostly labor.

Regulator-rectifier

The regulator-rectifier is one of the most common issues on all 3VD (MkI) TDM : the RR casing is badly designed and poorly cooled, resulting in overheating problems and a premature failure. A faulty regulator must be changed with no delay because it will usually fry the battery and kill all on-board electronics (ignition unit & rev counter). The regulator-rectifier may be proactively protected from overheating by moving it to a better ventilated location and/or adding an aluminum heat-sink. It may also be simply replaced by a more reliable MkII regulator.
• Years : 1991-1995.
• Check / Repair : check the regulator-rectifier output voltage, must be 14V @ 5000t/min. If the voltage is unstable or exceeds 15V the regulator-rectifier is defective.
• Difficulty : easy to check or replace.
• Expenses : in case you wait too much time, the worst may occur : r/r, battery, TCI, dash to replace !

Battery removal

The battery is not very easy to remove on all TDM850, this is a common subject on numerous internet forums.
See on the page about the battery.
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